Evaluating the real-world implementation of the Family Nurse Partnership in England: a data linkage study

Review approach

We conducted a literature review of the effect of FNP programmes on maternal and child outcomes using a combination of PubMed searches for ‘FNP’ or ‘Nurse Family Partnership’ (the original programme name in the USA) and identifying additional references through manual review of reference lists of previously identified papers from the USA, UK and other trials.

The evidence base for the FNP spans multiple countries and includes randomised controlled trials as well as a few non-randomised studies. Findings from this review were synthesised by the country in which the research was conducted, given differences in context and the importance of context (usual care) for the effect of interventions.

USA randomised trials

Most of the literature on the effectiveness of the FNP stems from three randomised trials of the Nurse Family Partnership (NFP) conducted in the USA by David Olds and colleagues, including over 20 peer-reviewed articles. The trials were conducted in Elmira, New York (enrolment 1978–80), Memphis, Tennessee (enrolment 1990–1) and Denver, Colorado (enrolment 1994–5). A wide range of maternal and child outcomes were examined, with up to 20 years of follow-up.

Overall, the evidence from the three USA trials indicates a positive effect on some – but not all – maternal and child health and educational outcomes. Often, the positive effect was observed in a subsample of particularly vulnerable mothers but not in the entire cohort. The Elmira trial found a one-third reduction in all accident and emergency (A&E) admissions among children up to age 2 and ages 2–4; however, no effect was observed on all hospital admissions ages 2–4. 25,26 Although a reduction in mean A&E and hospital admissions for injury/maltreatment of 55% was reported in the second year of life, no such effect was detected for injury/maltreatment in ages 0–1 or 2–4. No effect was observed on this outcome for up to 2 years in the Memphis trial. 27 The Elmira trial was the only NFP trial to examine child abuse/maltreatment reports and found a 40% reduction in such reports up to age 15 (although this benefit was not evident before the age of 4 years). 26,28

All three USA trials examined the effect of the NFP on child development and educational achievement. Results were mixed in the Elmira trial, with no effect up to age 4 for the whole sample and no effect on intellectual functioning at age 3 or 4 among children identified as maltreated. 26,29 There was no difference in intellectual functioning at age 3 or 4 among children of women smoking ≥ 10 cigarettes per day at enrolment; however, they did have higher intelligence quotient (IQ) scores (4.86 points on average) at this age than children of smoking mothers in the control arm. 30 The evidence in favour of a positive effect of the FNP was stronger in the Memphis and Denver trials, although these effects were concentrated in the subgroup of mothers with low psychological resources at enrolment (composite score including mental health, sense of mastery and intelligence scores), and even among this group, the positive effects were limited to only a few outcomes by age 6 and/or age 9 in the Denver trial. 31–36 Child mortality was only examined in the Memphis trial, which found no evidence of effect up to age 19 for all-cause mortality but a reduction in preventable-cause mortality in the NFP arm (0% vs. 1.6% in one control group, p = 0.04). 37

The effect of the NFP on maternal outcomes was weaker than on child outcomes. The Elmira trial found evidence of a 50% reduction in child abuse perpetration reports up to 15 years after giving birth. 28,38 There was evidence of 0.5 fewer subsequent births 15 years after the first birth among unmarried women of low socioeconomic status only in the Elmira trial but no evidence at 18 years in the Memphis trial or at 4 years in the Denver trial. However, there was evidence that NFP increased the subsequent birth interval by 5–28 months in all three trials (among the unmarried, low-socioeconomic subgroup in Elmira only). 32,34,38,39 There was no evidence of an effect on maternal educational qualifications beyond 6 months31,34,40,41 or on experience of domestic violence in the three trials (weak evidence of a decrease in the Denver trial). 28,34,42 Evidence was mixed regarding the effect on drug use or impairment. 34,38,42 The effect of NFP on maternal mortality was only examined in the Memphis trial, with no evidence of a difference in all-cause mortality but weak evidence of a 1% reduction for mortality from external causes at 20 years. 37

A more recent trial of 5670 Medicaid-eligible nulliparous pregnant mothers recruited between 2016 and 2020 in South Carolina found no evidence of an effect on birth outcomes (preterm birth, low birthweight, small for gestational age and perinatal death). 43

England Building Blocks randomised trial

One randomised controlled trial of the FNP (the Building Blocks trial) was conducted in England, enrolling approximately 1600 expectant mothers in 2009–10. 44 The Building Blocks trial found no evidence of effect on the four primary outcomes – smoking in late pregnancy, birthweight, second pregnancy within 24 months of first birth and rates of A&E attendance or hospital admissions within 24 months of birth. Some secondary outcomes suggested small positive impacts of the FNP in the first 2 years of life, including maternally reported child cognitive and language development. Safeguarding concerns recorded in primary care records were higher for mothers enrolled in the FNP.

Results for follow-up to age 6 showed no difference for most maltreatment outcomes between the trial arms, including referrals to social services, children referred as Children in Need (CiN), duration for which children were assessed as in Need, children with a child protection plan (CPP) or who were Looked After. 24 However, children in the FNP arm spent on average 2 months less time in care than children in the usual care arm. There was no evidence of a difference in children not attending a hospital outpatient appointment, attending A&E for injury or ingestion or being admitted to hospital for the same causes.

Nonetheless, there was evidence of FNP’s impact on some – but not all – child development and educational outcomes. There was no difference in Special Educational Needs (SEN) provision up to age 6 or educational attendance for ages 2–4. Children of FNP mothers were more likely to achieve a Good Level of Development at school entry (age 5) than in the usual care arm, with a greater beneficial impact on total point score (across 17 learning goals) observed for children of younger mothers. At Key Stage 1, children in the FNP arm were more likely to reach the expected level for reading; no other differences were observed for Key Stage 1 outcomes. The beneficial effects of the FNP were stronger among boys than girls (reading and writing), among younger mothers at enrolment (mathematics and writing) and among mothers not in employment, education or training at the time of enrolment (writing).

Other randomised trials in Germany, the Netherlands and Canada

Several other trials have been conducted in high-income countries. The VoorZorg trial in the Netherlands, enrolling in 2007–9, reported a reduction in child abuse/maltreatment reports by age 3 in the FNP arm, as well as a reduction in some types of interpersonal violence at 32 weeks of pregnancy and 24 months after birth. 45,46 A trial of a FNP-based model in Germany (Pro Kind) reported improved child development among high-risk women only, but no evidence of a difference in subsequent births within 2 years. 47 The follow-up trial evaluating outcomes at age 7 reported fewer behavioural problems in children, less child-abusive parenting, fewer maternal mental health problems and higher maternal life satisfaction in the intervention arm. 48 Some positive effects on mother–daughter interactions were also reported for a small subsample who agreed to participate in video recording. 49

One randomised controlled trial in Canada has not yet published results on primary outcomes but has reported preliminary findings on a number of secondary outcomes, with a reduction in prenatal cannabis use and a modest reduction in cigarette use in smokers associated with the intervention but no reduction in rates of prenatal cigarette and alcohol use. 50

Non-randomised studies in Australia, Scotland and the USA

Non-randomised studies in the USA and Australia have reported reduced preterm births, child maltreatment, infant death and subsequent births among FNP participants compared with controls, as well as higher high school attainment and different patterns of A&E attendance. 51–56 These studies adjusted for confounders through propensity score matching, frequency matching and entropy balancing, although due to limited maternal characteristics, the potential for residual confounding remains. The Australian study compared participants to eligible women who were not referred to and never participated in the programme, thereby also being subject to likely residual confounding. One prospective cohort study in Scotland has not yet reported results. 57

Other evidence

A randomised controlled trial of group FNP in England, administering 44 FNP sessions to groups of 8–12 expectant mothers, found no evidence of effect on parenting or maternal sensitivity or on secondary outcomes [except for a higher proportion of mothers breastfeeding at 6 months, odds ratio (OR) 3.2; 95% confidence interval (CI) 0.99 to 10.6]. 58

Synthesis

The available evidence on the effectiveness of the FNP is summarised in Appendix 1.

The three USA trials of FNP showed mixed but overall positive impacts on child health and development outcomes and some maternal outcomes, similar to the more recent Netherlands trial. These results contrast with the Building Blocks trial in England, which showed no evidence of impact of FNP on most child outcomes, with the exception of some cognitive outcomes. There are two main contributing explanations for the difference in results observed in England compared with the USA and the Netherlands: first, there are likely important differences in usual care contexts between different countries. The social safety net is likely to be stronger in England than in the USA, with better access to services for adolescent mothers not enrolled in FNP (including the minimum five mandated health visiting contacts, universal health care free at the point of care, services provided through free Children’s Centres, etc.), which may explain the lack of association for most outcomes in England. For example, the mothers in the control arm of the Building Blocks trial received an average 16 health visiting contacts up to the child’s second birthday. Nonetheless, the usual care group in the Netherlands trial probably had access to similar or better levels of care than in England, with 9–11 home visits before the child’s second birthday, as well as support from child welfare and mental health organisations,59 indicating that there are important factors (beyond access to services) shaping the effect of FNP.

Second, there are notable differences in the eligibility criteria for FNP in England compared with other countries. The main eligibility criterion for enrolment in FNP in England is maternal age: adolescents who are aged up to 19 at last menstrual period (LMP), and who are first-time mothers, are eligible for enrolment as long as they live in a LA with a FNP site and are enrolled before 28 weeks of pregnancy. From November 2016, a few FNP sites extended their eligibility criteria to enable enrolment after 28 weeks gestation and among mothers aged 20–24 at LMP with other markers of vulnerability, recognising that mothers in these groups could also benefit. 60 Eligibility criteria for the Building Blocks trial (nulliparous, age ≤ 19, living in the catchment area of a local FNP team, < 25 weeks of pregnancy)44 are therefore aligned with the practice in English FNP sites at that time. Young age is the main eligibility criteria for FNP in England, based on the ease of identifying the youngest adolescent mothers, associations between adolescent motherhood and social adversity, disrupted education and employment13,61 and other factors contributing to poor birth and health outcomes among their children. 5,6,62

In contrast, additional socioeconomic criteria such as unemployment, low educational level or low income are used in combination with maternal age in other countries,27,35,63 based on logic models of how the original NFP was expected to provide benefits. 64 As a result, the population of young mothers enrolled in trials in other countries are a more selected and vulnerable group than in England, who may stand to benefit more from the FNP (as evidenced by greater effectiveness in socioeconomically deprived groups demonstrated in the USA trials). 32,36,38

Hospital Episode Statistics – Hospital Admissions Data

Hospital records for mothers aged 13–24 years and their children in England were extracted from records of births and deliveries in HES. HES is a data warehouse containing details of all hospital admissions (from 1997), outpatient appointments (from 2003) and A&E visits (from 2010) at NHS hospitals in England. 72 HES data have been extensively used in research. In addition to the birth record, we linked information from hospital admissions and A&E attendances for mother and child (including up to 11 years before delivery for the mother; see Appendix 2, Figure 16).

Information captured in HES includes administrative data [including admission dates, NHS trust, general practitioner (GP) code]; demographic information (including age, sex, ethnicity) and clinical information (diagnoses and procedures). A unique ‘Hospital Episode Statistics Identifier (HESID)’ is assigned to enable episodes of care for the same individual to be combined (this has recently changed to a ‘Token Person ID’). Diagnoses are coded by professional coders in hospitals using International Classification of Diseases, 10th Revision (ICD-10) codes (International Classification of Disease, version 10); procedures are coded using Office of Population, Censuses and Surveys Classification of Surgical Operations and Procedures, version 4 codes (OPCS-4). 73,74 Based on previous methodological work, we linked delivery records for mothers and birth records for their children within HES to create a mother–baby HES cohort. 69

National Pupil Database – education and social care data for mothers enrolled or not in Family Nurse Partnership and their children

The HES cohort of mother–baby pairs were linked to education and social care records from the Department for Education for both mothers and children in FNP and comparison groups (including information before delivery for mothers). Information on assessments, attainment and progression at each Key Stage is available for all pupils in state schools in England, alongside eligibility for free school meals (FSM), information about SEN provision and information about absences and exclusions. NPD, including social care data, has been extensively used in research. 75

For both mothers and their children in the cohort, we linked HES data to the following NPD databases:

• The Spring School Census (formerly PLASC), the Early Years Census, the Pupil Referral Unit (PRU) Census and Alternative Provision – including pupil-level information from 2002 (for the School Census) for pupils aged 2–19+ on SEN, FSM eligibility and information about absences and exclusions.

• The CiN Census – including information on referrals to children’s social services, assessments carried out upon these children and whether the children became the subject of a CPP, from 2008. 76

• The Children Looked After (CLA) return – including information on all Looked After children and recent care leavers in England, from 2005. 77,78

For mothers only, we linked to Key Stages 2 and 4 data, which include teacher assessments and/or test results in Year 6 (age 11) and Year 11 (age 16). We also linked to Key Stage 5 data (Year 12–13, ages 17–18) but did not use these data due to small numbers. For children only, we linked to the Early Years Census and EYFSP. These data include whether the child achieved a Good Level of Development at school entry (age 5), which we used as a proxy for school readiness, as well as Key Stage 1 assessment data (age 7).

A Unique Pupil Number (UPN) is used by the Department for Education (DfE) for linkage of CLA and CiN with the NPD. The UPN is usually assigned at first entry to a maintained school or nursery, typically around the age of 4–5. Therefore, it is not possible to link the NPD to CLA or CiN data for children who receive social care services only before they enter nursery/school or for some adopted children (who can be provided with a new UPN). 79 It is not mandatory to return UPN in CLA or CiN beyond age 16. UPN was replaced by an anonymised Pupil Matching Reference in the data that we had access to.

Family Nurse Partnership information system – Family Nurse Partnership service data for mothers enrolled in Family Nurse Partnership

The HES cohort was linked to the Family Nurse Partnership information system (FNP IS) to obtain information on participation in FNP for mothers who were enrolled in FNP. The FNP IS supports the implementation of the FNP programme in England, originally provided by NHS Digital under contract to the FNP National Unit on behalf of Public Health England. Data are reported in real time and are used locally by FNP teams and nationally by the FNP National Unit to monitor programme delivery and support quality improvement.

Data collected in the FNP IS include information from the mother and child collected at enrolment (by 28 weeks gestation at the latest, including mother’s age, marital status, living arrangements, education, employment, social care); 36 weeks gestation (including maternal health, alcohol, drugs and smoking); birth (including birthweight and gestational age) and at regular intervals until 24 months after birth (including child health and development, social care and other maternal baseline variables). Information on each visit is also collected (including date, length of visit, family nurse seen and referrals to other services). The FNP IS became functional in 2009, and data quality was reported to be high from 2010 onwards. FNP data have been used in previous research. 80

The FNP IS contains maternal and child identifiers at enrolment/birth: name, sex, date of birth, postcode, GP code and NHS number. When mothers graduate from the FNP (mostly at the child’s second birthday, but sometimes earlier), pseudonymised data are retained only by the FNP National Unit, and identifiers are held solely on secure servers at NHS Digital.

The time span covered by each data source (including look-back, study and follow-up periods) is described in Appendix 2, Figure 16.

Linking mothers enrolled in Family Nurse Partnership to Hospital Episode Statistics

Linkage between data from the FNP IS and HES was conducted using deterministic linkage via NHS Digital (see Appendix 2, Tables 21 and 22). Of the 32,040 mothers in our FNP cohort who gave birth between April 2010 and March 2019, 31,560 (98.5%) were linked to a record in HES.

Characteristics of unlinked mothers

Appendix 2, Table 24, describes the characteristics of the 31,560 FNP mothers who linked to a HESID and the 480 FNP mothers who either did not link to a HESID (n = 10) or who linked to a likely incorrect HESID and were subsequently excluded (n = 470). Compared to mothers who linked to a HESID, unlinked mothers seemed to be a slightly more vulnerable group: they were less likely to be living with their mother (with or without their partner present) or to have any GCSEs at enrolment and more likely to have missing data. They had a lower mean number of FNP visits (26, compared with 35 for FNP mothers who linked to a HESID). They were more likely to be of black, South Asian or mixed/other ethnicity and living in London.

Description of linkage quality

Of the 31,560 FNP mothers included in our linked study cohort, 31,450 (99.7%) linked to HES via the FNP-HES linkage key at match rank 1 or 2, indicating high-quality links. Only 0.3% (n = 85) of mothers linked at match rank > 2, indicating less-certain links. Twenty-five mothers (< 0.1%) were linked to HES manually (see Appendix 2, Figure 17).

To check for potential false matches between FNP and HES, we assessed the agreement between information recorded separately in both data sources for all FNP mothers in our cohort who linked to at least one HES admitted patient care (APC) record (see Appendix 2, Table 25). Agreement between both data sources was generally high.

Mothers aged 13–19

There is a complex history of FNP sites in England, with site openings, closures, mergings and splits throughout the study period. In addition, the catchment area of FNP sites may have changed over time (e.g. a site may have been decommissioned for one LA in its catchment area but continue to operate in another).

We used FNP IS data to identify the first and last month-year in which expectant mothers aged 13–19 at LMP were enrolled in each FNP site based on the enrolment dates recorded in each participant’s record. We calculated start and end dates separately for each lower-tier LA in each FNP site in order to allow for changes in catchment area over time. We used the lower-tier LA recorded in FNP participants’ HES records because FNP IS records only upper-tier LA of residence at enrolment. Lower-tier LA was also used to identify the catchment area for each FNP site (e.g. the Hampshire FNP site included only a subset of lower-tier LAs in Hampshire). Inconsistencies were resolved through detailed consultation with the FNP National Unit, including consultation of site records. Nonetheless, some misclassification in catchment areas or activity dates remains likely, particularly before the FNP became commissioned by LA in October 2015, when Primary Care Trust level commissioning (with potentially non-overlapping boundaries compared with LAs) meant slight changes in catchment areas may have occurred at this time.

Activity dates and lower-tier LAs included in the catchment area for 122 FNP sites are included in Appendix 2, Table 26).

Mothers aged 20–24

As some sites had changed their eligibility criteria during the study period to allow some mothers aged up to 24 to be enrolled, we also planned to include mothers aged ≥ 20 in our analysis. We used FNP IS data to identify LAs that had extended their eligibility criteria to allow for recruitment of older mothers. We classified LAs as having extended criteria if at least 10 mothers aged 20–24 at LMP and giving birth up to 31 March 2019 were enrolled in the FNP. As with mothers aged 13–19, we defined site activity dates as the first and last month-year in which mothers aged 20–24 were enrolled in each site. We did not calculate different activity dates for lower-tier LAs in each site due to small sample sizes and because all but one site only included one lower-tier LA in their catchment area; see Appendix 2, Table 27).

Mothers aged 13–19

This study cohort included all 130,415 mothers aged 13–19 at LMP who had their first live birth between 1 April 2010 and 31 March 2019 and whose first antenatal booking appointment as recorded in HES (or estimated date of 28 weeks gestation, if missing) occurred on a date when the FNP was active in their LA of residence (Figure 2). Of these, 99,150 (76%) were never enrolled in FNP.

FIGURE 2.

Identification of FNP participants and comparison group among cohort of mothers aged 13–19. Note: numbers have been rounded to the nearest 5 in accordance with NHS Digital’s statistical disclosure rules for subnational analyses; totals may not be equal to the sum of component categories. ANC, antenatal care.

Date at LMP was estimated by subtracting gestational age at birth from the date of childbirth or subtracting 40 weeks (the median gestational age at birth among mothers aged 13–19 in our cohort) from the date of childbirth for the 13% of mothers with missing gestational age at birth. Mothers whose antenatal booking appointment occurred between 28 and 33 weeks gestation were excluded as they would not have met the eligibility criteria for the FNP (see Figure 2). This means we may have excluded a small number of eligible mothers within the few sites that allowed enrolment after 28 weeks from November 2016. Since we observed a spike in the number of mothers with a recorded gestational age at booking appointment of 33 weeks or more, we considered these to be data errors (6% of mothers) and recoded them to 28 weeks so that they could be retained within the cohort.

The creation of the study cohort of mothers aged 20–24 is described in Appendix 2, Figure 18.

Description of linkage

Linkage of all mothers and children in the study cohort to NPD education modules was performed by the DfE, following extraction of identifier information (including full name and postcode history) by NHS Digital. DfE used a matching algorithm requiring agreement (full or ‘fuzzy’) on names, date of birth and postcode; matching to NPD was not completed for names and date of birth only or on names and postcodes only (see Appendix 2, Table 28). Subsequent linkage to social care data was performed by DfE via the Pupil Matching Reference number.

Linkage of maternal Hospital Episode Statistics records to National Pupil Database

Of the 130,415 mothers aged 13–19 included in the study cohort, 109,635 (84.1%) were linked to a record in NPD (Figure 3). Mothers who were enrolled in FNP were slightly more likely to link (90%) compared with mothers who were not enrolled (82%). Overall, 98% of linked mothers linked at match strength 1, indicating fully confident matches.

FIGURE 3.

Description of linkage of the NPD and HES – mothers in cohort. Note: numbers have been rounded to the nearest 5 in accordance with NHS Digital’s statistical disclosure rules for subnational analyses.

Linkage of child Hospital Episode Statistics records to National Pupil Database

Among 128,270 children of mothers aged 13–19, 89,580 (69.8%) were linked to a record in NPD (Figure 4). Children born to FNP mothers were slightly less likely to link to NPD (68%) than those born to mothers not enrolled in FNP (71%). Overall, 97% of linked children linked at match strength 1, indicating fully confident matches.

FIGURE 4.

Description of linkage of the NPD to HES – children in cohort. Note: numbers have been rounded to the nearest 5 in accordance with NHS Digital’s statistical disclosure rules for subnational analyses.

Characteristics of unlinked mothers and children

There were some differences in the characteristics of mothers in the study cohort who were and were not linked to NPD (see Appendix 2, Table 29). Mothers who did not link to NPD were much less likely to be of white ethnicity (65% vs. 87% among all mothers who linked) and more likely to live in the most deprived quintile (52% vs. 47%) and to have reached 20 weeks of pregnancy at antenatal booking appointment (8% vs. 5%). However, unlinked mothers were less likely than linked mothers to have vulnerability indicators relating to a history of hospital admissions – those related to mental health, adversity and chronic conditions, as well as A&E attendance.

The FNP data gave more insight into the characteristics of those who did and did not link (see Appendix 2, Table 30). FNP mothers who did not link to NPD were more likely to be living alone or in care at enrolment and to attend their antenatal booking appointment after 10 weeks of pregnancy. However, they were less likely to be recorded as CiN, having a CPP or being a child in care during pregnancy.

There were also some differences in the characteristics of children in the study cohort who did and did not link to NPD (see Appendix 2, Table 31). Children who did not link to NPD were more likely to be born from 2016 onward, less likely to have a mother of white ethnicity and slightly more likely to live in less deprived areas.

Indicators of child maltreatment

We assessed the effect of FNP on indicators of child abuse and neglect, as measured by the percentage of mothers whose baby was discharged from hospital to social services at birth, whose child had at least one unplanned hospital admission for injury or maltreatment-related diagnoses or who died (up to age 2 or 7) or whose child was ever recorded as a Child in Need, as having a CPP, or being a Child Looked After (at age 4–5 years). ICD-10 code lists for injury or maltreatment-related diagnoses were based on previously published lists81,82 and are included in Appendix 3. As the UPN for linking education and social care data is usually assigned at school entry, social care data for children only involved with social care prior to school entry cannot be linked. Therefore, we only examined CPP, Child in Need and CLA status after school starting age (4–5 years). Thresholds for CiN status vary across the country: only assessments that have been ‘accepted’ are recorded within the data. The CiN data exclude some disabled children (those who are not receiving services from LAs) and children who are receiving support from LAs through early help services. 83 We did not have the primary need code in our data, and some children referred to social care services will be referred for reasons other than child maltreatment (e.g. child disability).

The potential for surveillance bias to distort the effect of early life interventions on child maltreatment has been extensively discussed, and nurse home visiting has been shown to result in increased contact with nurses, potentially leading to lower thresholds for referral to social care services for families enrolled in FNP than families who are not enrolled. 29,44,45 This bias in ascertainment of maltreatment may dilute or reverse the association between FNP participation and maltreatment. Conversely, it has also been hypothesised that a nurse’s closeness to participants may delay reporting of suspected maltreatment. 45 We examined CiN referral source, aiming to determine whether the proportion of referrals initiated by health visitors differed between children of mothers enrolled and not enrolled in FNP.

Child health, developmental and educational outcomes

We firstly described rates of preterm birth (< 37 weeks of pregnancy) and low birthweight (< 2500 g) between groups. We also described A&E attendance and unplanned hospital admissions for any diagnosis. These were reported as descriptive outcomes since the direction of effect could be interpreted positively or negatively (FNP participation might reduce the need for emergency care or alternatively increase appropriate care seeking). Nonetheless, they represent important outcomes for understanding the effects of FNP on care-seeking behaviour.

For children reaching school age, we examined the effect of the FNP on school readiness as measured by the percentage of each group achieving a Good Level of Development as recorded within the EYFSP (level 2 + across the combined five areas of learning at school entry) at age 5, persistent absence (absent for ≥ 10% of possible school sessions), achieving expected levels at Key Stage 1 (age 7) for Mathematics, Reading and Writing and recorded as having SEN provision. We also examined FSM eligibility (pupils are recorded as eligible if a claim for FSM has been made by them or on their behalf by their parents). We also calculated the percentage of children in each group recorded in the EYFSP as having attended nursery.

Maternal outcomes

For mothers, we evaluated unplanned hospital admissions for adversity-related reasons (violence, self-harm and drug/alcohol abuse) or for mental health-related diagnoses after delivery (see Appendix 3). As with child outcomes, A&E attendance and unplanned hospitalisations for any diagnoses were reported as descriptive outcomes. We also examined the effect of FNP participation on subsequent pregnancies within 18 months of the first live birth. We examined subsequent births within 18 months (rather than pregnancies within 24 months as measured in the Building Blocks trial) because 18-month birth intervals are associated with the highest risks of adverse outcomes for women and babies. 84,85 Amongst mothers who had not previously had the opportunity to take GCSEs (i.e. were < 16 at the start of the academic year in which they reached 20 weeks of pregnancy), we evaluated the percentage in each group who achieved 5 A*–C grades including English/Maths at GCSE level (or equivalent), in the 2 years after delivery. We did not evaluate A-level outcomes as these data were available for < 1% of mothers. Amongst mothers who would still have been school age in the year following the academic year in which they reached 20 weeks of pregnancy (i.e. those aged < 15 at the start of the academic year in which they reached 20 weeks of pregnancy), we evaluated the percentage in each group who were enrolled in school up to Year 11 during the 7 years following birth. We did not evaluate school outcomes past Year 11 or the proportion of mothers sitting GCSEs after Year 11, due to small numbers.

Follow-up cohorts

Outcome data were available for up to 7 years after delivery, but eligibility for each outcome depended on the child’s age. We therefore described outcomes (1) at birth, (2) in the 2 years following delivery and (3) in the 7 years following delivery. We describe the cohorts used for each set of outcomes in Table 2.

Descriptive analyses

We described maternal risk factors at the time of pregnancy, previous health and educational risk factors (see Table 3) and pregnancy outcomes for all mothers in our cohort according to enrolment in FNP. We further described maternal risk factors at enrolment and during pregnancy among mothers enrolled in the FNP (using risk factors collected in FNP IS, such as living arrangements and intimate partner violence).

Enrolment rate and maternal risk factors associated with enrolment in the Family Nurse Partnership (Objective 1)

We restricted the enrolment analysis to mothers giving birth between April 2010 and March 2017 for those aged 13–19 at LMP in order to use the same cohort for Objectives 2 and 3 (ensuring at least 2 years of follow-up for all mothers and their children in the cohort). We calculated enrolment rates as the percentage of FNP participants among eligible first-time adolescent mothers living in a LA with an active FNP site at the time of first antenatal appointment before 28 weeks of pregnancy, including by site and maternal risk factor (see Table 3). We also calculated the percentage enrolment for all first-time adolescent mothers in England (including areas not offering the FNP). Multilevel logistic regression models with mothers nested within FNP sites were used to calculate crude and adjusted ORs of enrolment. Multivariable models included all maternal risk factors; multicollinearity was assessed using Spearman correlation coefficients. To examine variation in maternal risk factors for enrolment, we stratified the analysis by site characteristics: we classified FNP sites with enrolment rates in the top quartile as ‘high-enrolment sites’ and those with enrolment rates in the bottom quartile as ‘low-enrolment sites’. We stratified the multivariable models according to high-/low-enrolment site, region and financial year of delivery and tested for interactions between these strata and each maternal risk factor. We explicitly classified mothers not linking to NPD as ‘unlinked’ in relevant variables to retain them in the models.

Lastly, we built crude and adjusted funnel plots of the percentage enrolled in each FNP site according to the size of the eligible adolescent mother population, separately for mothers aged 13–17 and 18–20 at childbirth, to assess the extent to which variation in enrolment rates across sites was likely to be due to chance. The outer limits on the plots define the range of percentages that are within three standard deviations (SDs) of the national average. If the observed variation was due to chance alone, we would expect only one in 500 sites to have a percentage that is outside these limits.

We conducted a secondary analysis for first-time mothers aged 20–24 at LMP living in LAs with FNP sites enrolling these older mothers. We used the FNP data to identify LAs that had extended their eligibility criteria as those where at least 10 mothers aged 20–24 at LMP and giving birth up to 31 March 2019 were enrolled in the FNP. We included mothers whose first antenatal appointment (or estimated date of 28 weeks gestation, if date missing) occurred from the month of enrolment of the first mother aged 20–24 in the local site.

We calculated the percentage enrolment as the percentage of FNP participants among the eligible study cohort, by site and across all sites. Multilevel logistic regression models of mothers nested within FNP sites were used to calculate crude and adjusted ORs of enrolment (adjusting for all risk factors). The two least-deprived IMD quintiles were grouped to account for smaller numbers. Sample size of FNP participants was too small for analyses stratified by time, region and high/low enrolment in this age group.

Effect of the Family Nurse Partnership on maternal and child outcomes (Objective 2)

We firstly described the outcomes of interest according to maternal risk factors and enrolment in the FNP.

We then compared outcomes for mothers ever enrolled in FNP, and their children, versus those never enrolled, using two analysis strategies to account for measured confounders related to FNP enrolment and outcomes. Propensity score matching aims to minimise bias, while adjustment for confounders aims to minimise variance.

Contextual factors associated with benefitting from Family Nurse Partnership (Objective 3)

Description of mothers in study cohort

Mothers who were enrolled in FNP were strikingly different from those who were never enrolled (Table 5). FNP mothers were younger, more likely to be admitted to hospital for adversity-related diagnoses or to attend A&E in the 2 years prior to 20 weeks of pregnancy and more likely to have their booking appointment after 20 weeks of pregnancy. FNP mothers were also more likely to have been in care or have a CPP, more likely to be recorded as having SEN provision, FSM and be in the most deprived quintile according to Income Deprivation Affecting Children Index (IDACI), more likely to have been excluded or be persistently absent and less likely to achieve 5 A*–Cs at General Certificate of Secondary Education (GCSE) level (but more likely to have achieved expected levels at Key Stage 1). Further information on the FNP cohort for mothers aged 13–19 based on data from the FNP IS is provided in Appendix 5, Table 33. Similar patterns were seen for mothers aged 20–24 (see Appendix 5, Tables 34 and 35).

Key messages

• Only 23.2% (95% CI 23.0% to 23.5%) were enrolled in the FNP (25,680 of 110,520 eligible mothers).

• Enrolment rates varied substantially across 122 sites (range: 11–68%), and areas with greater numbers of first-time adolescent mothers achieved lower enrolment rates.

• Mothers aged 13–15 were most likely to be enrolled (52%; adjusted OR 2.65, 95% CI 2.39 to 2.94 compared with 18- to 19-year-olds) but accounted for only 2% of all eligible mothers.

• Only 26% of adolescent mothers with markers of vulnerability (including living in the most deprived areas and previous mental health-related hospital admissions) were enrolled.

Enrolment among mothers 13–19

We restricted the study cohort to eligible mothers aged 13–19 giving birth between April 2010 and 2017. Among all 110,520 eligible mothers, 25,680 (23.2%; 95% CI 23.0% to 23.5%) were enrolled in the FNP. This percentage ranged across 122 FNP sites, from 11% in Cumbria to 68% in Wandsworth (Figure 6). Appendix 2, Table 26, describes the 136 LAs, enrolment dates and FNP enrolment rates by FNP site.

FIGURE 6.

Percentage enrolment in the FNP among eligible mothers aged 13–19, living in a LA with an active FNP site at the time of first antenatal appointment, by LA – England, births between 1 April 2010 and 31 March 2017. Note: the 122 FNP sites active during the study period covered 136 LAs (numbers and geographic boundaries of sites and LAs changed over the study period). Different sites were active for different periods within the 2010–7 cohort; the FNP was never commissioned in 15 LAs (see Figure 1).

Overall, 12.5% (95% CI 12.4% to –12.7%) of all (25,680–204,690) first-time mothers aged 13–19 giving birth in England between March 2010 and April 2017 were enrolled in the FNP.

Risk factors for enrolment among mothers aged 13–19

Most eligible first-time mothers aged 13–19 in LAs with active FNP sites were white (85%), aged 18–19 at the time of birth (55%) and living in the most deprived quintile (49%) (Table 6). Five per cent of first-time adolescent mothers had ever been Looked After before 20 weeks of pregnancy, 32% had ever been persistently absent and 63% had attempted but not achieved 5 A*–C GCSEs. Characteristics of eligible mothers were similar between LAs that commissioned or had never commissioned FNP (see Appendix 5, Table 36). Overall, 66% of adolescent mothers in the eligible population had at least one vulnerability marker.

The percentage of eligible mothers enrolled in the FNP was highest (52%) among those aged 13–15 years than 20 years old at childbirth (12%), although 13- to 15-year-olds accounted for only 2% of eligible mothers. The percentage of eligible adolescent mothers enrolled increased slightly from 21% in the least deprived quintile to 24% in the most deprived. Forty per cent of adolescent mothers with a history of mental health- or adversity-related admissions were enrolled, as well as 44% of mothers ever Looked After. Overall, 26% of adolescent mothers with any vulnerability marker were enrolled.

Results from the adjusted model (see Table 6) showed that younger mothers were prioritised for enrolment [the OR decreased from 2.65 (95% CI 2.39 to 2.94) in 13- to 15-year-olds to 0.56 (95% CI 0.53 to 0.59) in mothers aged 20, compared to 18- to 19-year-olds]. Other risk factors included ever been a CLA (OR 1.92, 95% CI 1.81 to 2.04), ever had a CPP (OR 1.62, 95% CI 1.46 to 1.80) and ever identified as having SEN provision (OR 1.22, 95% CI 1.18 to 1.27).

Stratified analyses according to site enrolment level, English region and year of delivery among mothers 13–19

Low-enrolment FNP sites included 51% of all eligible mothers in their catchment areas but enrolled ≤ 21% of mothers in their catchment area, while high-enrolment sites included 9% of all eligible mothers and enrolled > 36% of mothers in their area (see Appendix 5, Table 37).

The effect of age and ethnicity on enrolment was more pronounced in low-enrolment sites (see Appendix 5, Table 38). The association between enrolment and age, ethnicity and deprivation varied across regions (see Appendix 5, Table 39). The age gradient appeared in all regions but was particularly pronounced in the South-West, East Midlands and South-East. In five of nine regions, mothers living in the most deprived areas were more likely to be enrolled than those in the middle quintile of deprivation. Conversely, London was the only region in which enrolment was higher in the least deprived areas (OR 1.68, 95% CI 1.08 to 2.63, compared with the middle quintile).

Risk factors for enrolment also varied over time (see Appendix 5, Table 40), in part due to changes in regional distribution of active sites.

Funnel plots of variation in enrolment rates

A substantial proportion of FNP sites’ enrolment rates fell outside the funnel plot limits, indicating that much of the variation in enrolment rates across sites for younger mothers (aged 13–17 at childbirth) was unexplained by chance (Figure 7). There was even more unexplained variation among mothers aged 18–20 at childbirth, as indicated by the majority of FNP sites falling outside the funnel plot limits. Among both age groups, adjusted enrolment rates were lower than expected in sites with larger numbers of eligible adolescent mothers (see Appendix 5, Figure 27).

FIGURE 7.

Unadjusted funnel plots of variation in FNP enrolment rates among eligible first-time mothers aged 13–19 across FNP sites, by maternal age, births between April 2010 and March 2017.

Key messages

• We found no evidence of an association between FNP and indicators of child maltreatment, except for an increased rate of unplanned admissions for maltreatment/injury-related diagnoses up to age 2 for children born to FNP mothers.

• There was weak evidence that children born to FNP mothers were more likely to achieve a Good Level of Development (school readiness) at age 5 than those born to mothers who were not enrolled.

• Mothers enrolled in FNP were less likely to have a subsequent delivery within 18 months of the index birth than those not enrolled.

Descriptive analysis of outcomes of interest according to maternal risk factors

Birth, child and maternal outcomes varied substantially according to maternal risk factors (see Appendix 6). For example, children were more likely to be admitted to hospital for maltreatment or injury if they were born to younger mothers, those living in more deprived areas, those with a history of hospital admissions for adversity or mental health-related admissions, those with contact with social care services as a child and those with lower levels of education.

Descriptive (unadjusted) analysis of outcomes of interest according to enrolment in Family Nurse Partnership

Propensity score matching

The best-fitting model for the propensity score was a multilevel probit model, with mothers clustered in FNP sites. We included as predictors all available maternal risk factors up to 28 weeks gestation (at which point the vast majority of mothers had been enrolled) listed in Table 3. We also included interactions between maternal age and year of delivery and maternal age and gestational age at booking. We explicitly modelled the missing data categories for unknown ethnicity and mothers who did not link to NPD, as this provided a better balance between groups than using the missingness pattern information approach. There was a good overlap of propensity scores between FNP and non-FNP mothers, meaning that there were many mothers who were not enrolled in the FNP who had similar risk factors to those who were enrolled (see Appendix 7, Figure 28).

The most balanced groups were achieved by using one-to-one matching without replacement with a calliper width of 0.01. Using this approach, the mean difference in propensity scores between groups was < 0.001. The standardised differences of key maternal risk factors were small (effect sizes of 0.2, 0.5 and 0.8 are considered to be small, medium and large effect sizes, respectively; see Appendix 7, Table 48). 95 However, since FNP mothers tended to have higher propensity scores (median = 0.39) than non-FNP mothers (median = 0.31), there were a small number of FNP mothers for whom we were unable to find a match (see Appendix 7, Figure 29). When matching the entire cohort of mothers aged 13–19 giving birth between 2010 and 2019, we were able to include 94.9% of mothers in the matched analysis. For the cohort with 2 years of follow-up (births between April 2010 and March 2017), we matched 95.7% of FNP mothers, and for the cohort with 7 years of follow-up (births between April 2010 and March 2011), we matched 99.9% of FNP mothers. The comparatively lower match rates for the later years were due to a smaller number of untreated mothers for these years. Using matching with replacement may have increased the proportion of matched mothers further but would have led to increased imbalance between groups.

Outcomes within matched cohort

Indicators of child maltreatment

There was an increased risk of unplanned admissions for maltreatment/injury-related diagnoses in the 2 years following birth amongst children of mothers who were enrolled in the FNP compared with those who were not (RR 1.15, 95% CI 1.07 to 1.24). There was weak evidence that FNP was associated with an increased risk of a hospital record indicating discharge to social services at birth (RR 1.23, 95% CI 1.00 to 1.51; p-value 0.046) and a decreased risk of a CPP up to 7 years after birth (RR 0.84, 95% CI 0.71 to 1.00; p-value 0.049). There were no other differences between groups in any of the indicators of child maltreatment that were evaluated (Table 10, Figure 8). Due to small numbers, we did not calculate RRs for the percentage of CiN referrals from health visitors.

FIGURE 8.

Indicators of child maltreatment: adjusted RRs and 95% CIs comparing outcomes for mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy.

FIGURE 9.

Child health, developmental and educational outcomes: adjusted RRs and 95% CIs comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy. KS1, Key Stage 1.

FIGURE 10.

Maternal outcomes: adjusted RRs and 95% CIs comparing outcomes for mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy. a, Among mothers who were aged < 16 at the start of the academic year in which they reached 20 weeks gestation. b, Among mothers who were aged < 15 at the start of the academic year in which they reached 20 weeks gestation.

TABLE 10 - Relative risks and 95% CIs for indicators of child maltreatment comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 in the propensity-score-matched cohort

Variables for adjustment were those from Table 3; different models were adjusted for different variables according to the model of best fit.

Note

Numbers have been rounded to the nearest 5, and cell sizes < 10 have been suppressed, in accordance with NHS Digital’s and DfE’s statistical disclosure rules for subnational analyses.

	N (%) in mothers enrolled in FNP (treated)	N (%) in mothers never enrolled in FNP (untreated)	AdjustedRR (95% CI)a
Birth outcomes (Births between April 2010 and March 2019)
Total with information at discharge	28,995	28,710
Discharge to social services	215 (0.7)	180 (0.6)	1.23 (1.00 to 1.51)
Child outcomes – within 2 years (Births between April 2010 and March 2017)
Total with information on health outcomes within 2 years	24,240	23,790
≥ 1 unplanned admission for maltreatment or injury	1605 (6.6)	1385 (5.7)	1.15 (1.07 to 1.24)
Child outcomes – within 7 years Births between April 2010 and March 2012
Total with information on health outcomes within 7 years	4330	4310
≥ 1 unplanned admission for maltreatment or injury	595 (13.6)	575 (13.2)	1.03 (0.93 to 1.14)
Total with information on social care outcomes within 7 years	3215	2965
CLA	85 (2.6)	85 (2.9)	0.91 (0.68 to 1.21)
CPP	165 (5.1)	180 (6.1)	0.84 (0.71 to 1.00)
CiN referral	830 (19.0)	785 (18.0)	0.99 (0.91 to 1.07)

Child health, developmental and educational outcomes

There was an increased risk of low birthweight amongst mothers who were enrolled in the FNP versus those who were not (RR 1.07, 95% CI 1.02 to 1.13). There was also an increased risk of unplanned admission for any diagnoses (in the 2 years following birth) and for A&E attendances (in the 2 and 7 years following birth).

There was weak evidence that children born to FNP mothers were more likely to achieve a Good Level of Development (school readiness) at age 5 (RR 1.05, 95% CI 1.00 to 1.09) than those born to mothers who were not enrolled. Children in the FNP arm were also more likely to be recorded as having FSM (see Table 11, Figure 9).

TABLE 11 - Relative risks and 95% CIs for health, developmental and educational outcomes comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 in the propensity-score-matched cohort

KS1, Key Stage 1.

Variables for adjustment were those from Table 3; Different models were adjusted for different variables according to the model of best fit.

Results for different domains of the GLD are provided in Appendix 8, Table 50).

Note

Numbers have been rounded to the nearest 5, and cell sizes < 10 have been suppressed, in accordance with NHS Digital’s and DfE’s statistical disclosure rules for subnational analyses.

	N (%) in mothers enrolled in FNP (treated)	N (%) in mothers never enrolled in FNP (untreated)	Adjusted RR (95% CI)a
Birth outcomes (Births between April 2010 and March 2019)
Total with information on gestational age at birth	26,485	27,375
Preterm birth (< 37 weeks of gestation)	2465 (8.4)	1375 (8.0)	1.04 (0.99 to 1.00)
Total with information on birthweight	26,740	27,625
Low birthweight (< 2500 g)	2345 (7.9)	2240 (7.6)	1.07 (1.02 to 1.13)
Child health outcomes – within 2 years (Births between April 2010 and March 2017)
Total with information on health outcomes within 2 years	24,240	23,790
≥ 1 unplanned admission for any diagnosis	9705 (39.7)	9110 (37.3)	1.06 (1.03 to 1.09)
≥ 1 A&E attendance	13,435 (54.9)	12,235 (50.0)	1.04 (1.03 to 1.05)
≥ 1 outpatient referral	5110 (21.1)	4455 (18.7)	1.10 (1.07 to 1.12)
Did not attend ≥ 1 outpatient appointment	1990 (46.0)	1860 (43.2)	1.11 (1.06 to 1.15)
Child health outcomes – within 7 years (Births between April 2010 and March 2012)
Total with information on health outcomes within 7 years	4330	4310
≥ 1 unplanned admission for any diagnosis	2200 (50.5)	2225 (51.0)	1.01 (0.96 to 1.05)
≥ 1 A&E attendance	3945 (90.5)	3800 (87.2)	1.03 (1.02 to 1.05)
≥ 1 outpatient referral	18,460 (75.5)	17,285 (70.7)	1.05 (1.02 to 1.08)
Did not attend ≥ 1 outpatient appointment	3430 (78.7)	3265 (74.9)	1.07 (1.01 to 1.12)
Child developmental/educational outcomes – within 7 years (Births between April 2010 and March 2012)
Total with information on nursery attendance	4090	4040
Nursery attendance	3915 (89.8)	3870 (88.8)	1.00 (0.99 to 1.01)
Total with information on EYFSP	3990	3955
Good Level of Development (school readiness)b	2295 (57.5)	2190 (55.4)	1.05 (1.00 to 1.09)
Total with information on Key Stage 1 attainment	4270	4260
Expected levels at KS1 (maths)	2550 (58.5)	2485 (57.0)	0.98 (0.95 to 1.02)
Expected levels at KS1 (reading)	2600 (59.6)	2490 (57.1)	1.00 (0.96 to 1.04)
Expected levels at KS1 (writing)	2225 (51.0)	2180 (50.0)	0.97 (0.93 to 1.02)
Total with information on SEN/FSM	4060	4010
SEN provision	1105 (25.3)	1025 (23.5)	1.06 (0.99 to 1.14)
FSM	2265 (51.9)	2035 (46.7)	1.09 (1.04 to 1.14)
Total with information on absence	4090	4040
Persistent absence	2530 (61.9)	2450 (60.6)	1.01 (0.97 to 1.04)

Maternal outcomes

Mothers who enrolled in the FNP were more likely to have unplanned admissions for adversity-related diagnoses, mental health conditions or any diagnoses and A&E attendances in the 2 and 7 years following birth, compared to those who were not enrolled (see Table 12, Figure 10). However, these mothers were less likely to have a repeat pregnancy within 18 months of the index birth (RR 0.92, 95% CI 0.88 to 0.97).

TABLE 12 - Relative risks and 95% CIs for maternal outcomes comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 in the propensity-score-matched cohort

Variables for adjustment were those from Table 3; Different models were adjusted for different variables according to the model of best fit.

Note

Numbers have been rounded to the nearest 5, and cell sizes < 10 have been suppressed, in accordance with NHS Digital’s and DfE’s statistical disclosure rules for subnational analyses.

	N (%) in mothers enrolled in FNP (treated)	N (%) in mothers never enrolled in FNP (untreated)	Adjusted RR (95% CI)a
Maternal outcomes – 2 years (Births between April 2010 and March 2017)
Total with information on health outcomes within 2 years	24,455	24,455
≥ 1 unplanned admission for adversity-related diagnoses	605 (2.5)	485 (2.0)	1.27 (1.15 to 1.41)
≥ 1 unplanned admission for mental health-related diagnoses	950 (3.9)	745 (3.0)	1.29 (1.18 to 1.41)
≥ 1 unplanned admission for any diagnosis	4860 (19.9)	4520 (18.5)	1.08 (1.04 to 1.12)
≥ 1 A&E attendance	13,610 (55.7)	12,750 (52.1)	1.06 (1.04 to 1.08)
Subsequent delivery within 18 months	2065 (8.4)	2270 (9.3)	0.92 (0.88 to 0.97)
Total eligible for and with information on GCSEs	2825	2765
5 A*–Cs at GCSE level	330 (11.7)	255 (9.2)	1.12 (0.96 to 1.29)
Total eligible for and with information on school enrolment	770	680
School enrolment	620 (80.5)	570 (83.8)	0.96 (0.92 to 1.01)
Maternal outcomes – 7 years (Births between April 2010 and March 2012)
Total with information on health outcomes within 7 years	4360	4360
≥ 1 unplanned admission for adversity-related diagnoses	345 (7.9)	300 (6.9)	1.16 (1.03 to 1.30)
≥ 1 unplanned admission for mental health-related diagnoses	435 (10.0)	385 (8.8)	1.18 (1.04 to 1.33)
≥ 1 unplanned admission for any diagnosis	2080 (47.7)	2040 (46.8)	1.02 (0.98 to 1.06)
≥ 1 A&E attendance	3775 (86.6)	3665 (84.1)	1.03 (1.01 to 1.05)

Subgroup analyses

Although there was variation in the association between FNP and outcomes across subgroups, there were no statistically significant interactions between enrolment in FNP and maternal age, ethnicity, area-level deprivation, maternal contact with social care services, child sex or year of delivery (see Figures 11–14, Appendix 7, Appendix 8, Figures 31–34). However, we did observe a significant interaction between region and subsequent births within 18 months (p = 0.0018). The reduction in subsequent births associated with FNP was seen most strongly in the South-West, South-East and London (see Appendix 8, Figure 33).

FIGURE 11.

Child unplanned admissions for maltreatment/injury in the 2 years following birth: subgroup analysis presenting adjusted RRs and 95% CIs comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy.

FIGURE 12.

Good level of development: subgroup analysis presenting adjusted RRs and 95% CIs comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy.

FIGURE 13.

Subsequent delivery within 18 months: subgroup analysis presenting adjusted RRs and 95% CIs comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy.

FIGURE 14.

Maternal unplanned admissions for any diagnosis in the 2 years following delivery: subgroup analysis presenting adjusted RRs and 95% CIs comparing mothers enrolled in the FNP vs. mothers who were not enrolled, for mothers aged 13–19 and giving birth in an area in which FNP was offered at the time of pregnancy.

Sensitivity analyses

We performed two sensitivity analyses where the approach to propensity score matching was changed to allow matching (1) within the same LA but in different time periods (comparing FNP mothers with similar mothers before FNP was offered in that LA) and (2) within the same time period but in different LAs (comparing FNP to similar mothers living in different LAs). It was more difficult to find closely matched groups within these sensitivity analyses since the characteristics of mothers differed over time and between LAs that did or did not offer the FNP. We therefore also present results from a matching with replacement strategy, aiming to retain a higher coverage of FNP mothers (see Appendix 2, Table 31). Results from these sensitivity analyses did not differ substantially from those of the main analysis.

Multivariable regression (adjusted) analyses

Effect estimates from the sensitivity analyses using multivariable regression (see Appendix 9, Tables 55–57) were broadly similar to those from the main propensity score analysis, with some differences between groups being attenuated.

Key messages

• Fifty-eight per cent of mothers enrolled in FNP completed the programme, and 42% left early.

• Mothers enrolled in FNP received an average of 38 visits and 42 hours of contact time with a family nurse.

• Fifty-nine per cent of mothers in pregnancy, 65% in infancy and 61% in toddlerhood met targets for the expected number of visits.

• Younger mothers and those with a history of unplanned hospital admissions for mental health, adversity or chronic health conditions, received a greater number of visits; other contextual factors, including nurse characteristics and area-level characteristics, had little effect on the number of visits received.

• Meeting the target for the number of expected visits in pregnancy was associated with a reduction in subsequent births within 18 months; meeting the target in infancy and toddlerhood was associated with an increase in the number of children with unplanned hospital admissions for maltreatment/injury up to age 2.

Description of attrition, fidelity targets and dosage in the Family Nurse Partnership

Of the 31,260 mothers aged 13–19 at LMP enrolled in FNP and giving birth between 2010 and 2019, with linkage to HES (see Figure 2), 28,155 gave birth before January 2018 and were included in this analysis. Of these, 28,120 had at least one visit recorded, 16,305 (58%) completed the programme and 42% left early (slightly higher than the target attrition rate of 40%). A small number of clients had some interrupted periods of enrolment where they left the programme and returned later on (see Appendix 4).

On average, mothers received a total of 38 visits during their enrolment in the FNP (Table 13), corresponding to an average 42 hours of contact time with a family nurse.

At each stage of the programme, there is a target number of visits that mothers should receive, and fidelity to these targets is measured (see Table 4). Mothers are expected to receive at least 80% of the maximum number of visits during pregnancy, 65% during infancy and 60% during toddlerhood. FNP also has targets for attrition: no more than 10% during pregnancy, 20% during infancy and 10% during toddlerhood.

Participant, programme and nurse characteristics associated with dosage in the Family Nurse Partnership

There was substantial variation in whether sites met delivery targets for each stage of the programme, illustrated by the lack of overlap in CIs in Figure 15.

FIGURE 15.

Percentage of mothers meeting fidelity targets for the number of expected visits in pregnancy, infancy and toddlerhood, according to FNP site, for births between April 2010 and January 2018 to mothers aged 13–19 at LMP. The solid line indicates the fidelity target.

Younger mothers and those with a history of unplanned hospital admission for mental health, adversity or chronic health conditions received a greater number of visits over their time in the programme (see Appendix 10, Table 58). There was little variation in the average number of visits or proportion of mothers meeting fidelity targets according to nurse characteristics (see Appendix 10, Table 59). However, we did see some patterns according to the number of visits with a partner present: mothers whose partner was present for 10–50% of visits tended to receive more visits than those whose partner was never present or those whose partner was present for > 50% of visits. A similar pattern was seen with the presence of parents.

When adjusting for all these maternal factors (Table 14), the greatest drivers of meeting fidelity targets in the pregnancy stage were maternal age (RR 1.13, 95% CI 1.08 to 1.19 comparing mothers aged 13–15 with those aged 18–19), having a history of adversity (RR 1.06, 95% CI 1.02 to 1.09 compared to mothers with no history of adversity), being a CiN at enrolment (RR 1.18, 95% CI 1.14 to 1.21 compared to mothers not CiN at enrolment) and having a CPP at enrolment (RR 1.20, 95% CI 1.14 to 1.26). Mothers who had ever been recorded with persistent absence or who had been excluded were less likely to meet targets, and those who had achieved 5 A*–C GCSEs prior to enrolment were more likely to meet targets (see Table 14).

The greatest driver of meeting fidelity targets during the infancy and toddlerhood stages was having met the targets in the previous stages of the programme (Tables 15 and 16). The area-level factors we explored (% of mothers in the area who were adolescents, ethnic distribution, % of preterm births, % of mothers smoking at delivery and rates of referrals to children’s social care or CPPs) did not have a significant association with meeting fidelity targets, except for LA-level deprivation, where mothers in the most deprived LAs were more likely to have the expected number of visits.

Effect of programme and contextual factors and dosage on outcomes

Within the group of mothers enrolled in FNP, none of the additional participant, programme or nurse characteristics (see Appendix 10, Table 59) were associated with child unplanned admissions for maltreatment or injury up to age 2, a Good Level of Development at age 5 (school readiness), maternal unplanned admissions for any diagnosis in the 2 years following birth or subsequent births within 18 months.

However, we observed that meeting the target for the number of expected visits in pregnancy was associated with a reduction in subsequent births within 18 months (RR 0.87, 95% CI 0.78 to 0.97 compared with mothers who did not meet the target in pregnancy, Table 17). Meeting the target in infancy and toddlerhood was associated with an increase in the number of children with unplanned hospital admissions for maltreatment/injury up to age 2 (Table 17).

Summary of main results

This study fills an important evidence gap in coverage and targeting of intensive home-visiting services such as FNP within England. We show the most vulnerable mothers are being targeted for FNP, especially the youngest adolescents and those with prior contact with children’s social care. However, our findings indicate insufficient commissioning of FNP relative to local needs: only 23% of eligible mothers in FNP catchment areas were enrolled (2010–7), and areas with the greatest numbers of adolescent mothers had lower enrolment rates. Overall, 26% of eligible mothers aged 13–19 with vulnerability markers associated with adverse outcomes were enrolled, including 52% of those aged 13–15, 44% of those ever recorded as being Looked After and 40% of those with prior mental health- or adversity-related hospital admissions. These groups represent mothers and infants at significantly greater risk of low birthweight, unplanned hospital admissions for injury and infant mortality. 89 We did not find any differences in the populations of mothers in areas that did and did not commission FNP.

Comparison with existing evidence

To our knowledge, this is the first study examining enrolment in a targeted intensive home-visiting programme for expectant mothers. Two previous studies have shown high variation in acceptance rates for universal home visiting between sites, with higher acceptance rates among higher-risk mothers. 103,104 In a similar targeted home-visiting intervention for vulnerable families in Canada (Families First), unenrolled mothers were more vulnerable than enrolled mothers – contrary to our findings – illustrating that it can be difficult to enrol the most vulnerable groups. 105

Interpretation

Budget cuts since the inception of the FNP in England in 2007 mean that the programme, costing approximately £3000 per client per year, has been offered to a more select group of mothers over time. 80,106 This study demonstrates FNP places are not commissioned proportionately to the number of adolescent mothers within local areas, contrary to the stated aims of prioritising ‘areas with […] the highest numbers of eligible population’. 107 Pregnant adolescents living in areas with many adolescent mothers are less likely to receive support than those in areas with few adolescent mothers, with important implications for equity.

Young age is the main eligibility criterion for FNP in England, based on ease of identification, associations with social adversity, disrupted education and employment13,61 and other factors contributing to poor health outcomes among their children. 5,6,62 Unlike some other countries, FNP eligibility criteria in England do not include low educational level or unemployment,27,35,64 which is informed by evidence of higher effectiveness in socioeconomically deprived groups in the US. 32,36,38 In our analysis, only half of mothers aged 13–15 living in areas in which FNP was commissioned were enrolled. Given strict caseload limits (maximum 25 mothers per Family Nurse), many sites in England have explicit policies of prioritising younger adolescent mothers. Overall, 74% of eligible mothers with vulnerability markers were not enrolled in FNP, indicating opportunities for improving policy and commissioning to address vulnerable mothers’ needs, with important and unexplained variation in who is offered intensive services across England.

There are several explanations and implications of this. First, FNP teams may prioritise mothers with additional vulnerabilities not captured in administrative data we used (homelessness or community mental health service use; Box 1), but it is likely that family nurses do not have the full picture of family vulnerability when prioritising services, and some vulnerabilities (such as family violence) may be disclosed only after a trusting relationship is built with their family nurse or health visitor. 108–110 This underscores the need for effective universal services which can identify those at greatest need for intensive services.

Second, there is uncertainty regarding which vulnerable mothers are most likely to accept and benefit from intensive support. Given insufficient funding to offer the programme to all eligible mothers, family nurses and referring providers need standardised, real-time information on vulnerabilities for all mothers to support decision-making and better target the FNP, alongside effective communication between health visitors and family nurses. Ongoing work on defining vulnerabilities by the FNP National Unit will support sites to determine priority criteria for their local context.

Third, vulnerable mothers may have higher refusal rates. Although FNP’s fidelity target is to enrol 75% of mothers offered FNP, aggregate site data suggest not all sites meet this target. We were unable to determine whether under-representation of some groups, for example, South Asian adolescent mothers, was because they were less likely to be offered a place to accept it or both. FNP teams report that most mothers who decline feel socially well-supported, although some decliners are especially vulnerable (e.g. involved with social care services). 111 Last, more vulnerable mothers may be unknown to midwifery services due to presenting to a booking appointment after 28 weeks (or because of moves between LAs in pregnancy). Individual-level information on who is approached and who accepts would help inform strategies to increase uptake among especially vulnerable mothers.

Summary of main results

Comparison with existing evidence

We were able to use data for almost all eligible mothers ever enrolled in the FNP since 2010 in England, excluding 1360 mothers who did not agree for their data to be used for research. Although we cannot know what the characteristics of the declining mothers are, the high coverage of our cohort means that our results are likely highly generalisable to the eligible population. We were able to link 99% of FNP mothers to a health record, and 98% of these to their baby’s health record.

Linked education data were available for 83% of mothers aged 13–19 (who were born between 1991 and 2006). These linkage rates are similar to those of other studies linking with NPD: 83% of Millennium Cohort Study children (born 2000–1) and 85% of Case Register Interactive Search Child and Adolescent Mental Health children (CRIS CAMHS, children referred between 2008 and 2013) were linked to the NPD. 112 In the study, mothers who could not be linked to NPD were more likely to be older, less likely to be white, more likely to be living in the most deprived areas and less likely to have had hospital admissions in the 2 years prior to 20 weeks of pregnancy. Similar differences in the characteristics of linked and unlinked individuals have been observed in another evaluation of linkage between HES and NPD, which found that the most deprived pupils and those in ethnic minority groups were less likely to link. 71 Such differential linkage is widespread and represents a problem of inequality, whereby particular groups and ethnicities are excluded from research based on analyses of linked administrative data or are less likely to link to information on risk factors or outcomes, meaning they are more likely to have their needs underestimated. 113

Numbers of children classified as CiN in our cohort (22%) was similar to those observed in the Building Blocks trial, which found that 21.5% of children were ever classified as CiN. Since we cannot identify children who were in contact with children’s social care services only before school entry (due to the way in which identifiers are assigned in the DfE data), these estimates likely underestimate true numbers of referrals. Other studies have shown that a large proportion of CiN occurs in preschool children: based on information from a Freedom of Information request, Bilson et al. estimated that 14% of children born between 2009 and 2010 were CiN before their fifth birthday. 114 Based on model estimates using data from the NPD, Jay et al. estimate that 25% of children are ever classed as CiN before age 16. 115

Rates of CPPs were lower in our cohort (4.5% overall and 5.1% in the FNP group) than in the Building Blocks trial (6.8% in the FNP arm and 6.6% in the usual care arm), and rates of CLA were also lower (2.0% in our cohort overall and 2.6% in the FNP group compared with 3.6% in the FNP arm and 3.3% in the usual care arm of the trial). Numbers of CLA in our study population were higher than those observed in the general population, including children born to older mothers. For example, a study of the cumulative incidence of CLA using NPD data found that 1.5% of children born in 2004–6 were ever Looked After by age 6, with increasing rates over time. 78 This may be due to the inclusion of all children recorded as CLA in our data, irrespective of the primary need code.

Our findings of no difference in CiN or CLA between groups mirror those of the Building Blocks 2–6 evaluation, which also found no difference in the timing or first referral, duration or primary need for CiN. 24 The Building Blocks evaluation did find that CLA in the FNP arm were in care for a shorter period of time compared with children in the usual care arm. We did not evaluate duration of periods of care in this study.

In the study, we found that 75% of children had an unplanned hospital admission or A&E attendance in the 2 years following birth (37% had an unplanned hospital admission and 72% had an A&E attendance). This was comparable to rates seen in the Building Blocks trial, where 81% of the FNP arm and 77% of the usual care arm had an unplanned hospital admission or A&E attendance. 99

The proportion of children achieving a Good Level of Development (school readiness) in our cohort was 58%, which was the same as reported in the FNP arm of the Building Blocks trial. 24 Percentages of children reaching the expected standard at Key Stage 1 for Reading and Maths were also similar (65% and 63% compared with 65% and 62%, respectively). Key Stage 1 Writing results were less comparable, due in part to increases in rates of children reaching the expected levels over time, as described in detail in the Building Blocks 2–6 report. 24

Our finding of a reduction in rapid repeat pregnancies in mothers enrolled in the FNP differs to findings from the Building Blocks trial, which observed no evidence of an effect on subsequent pregnancies within 24 months of the first birth. This may in part be due to differences in definitions: we only captured pregnancies that resulted in a live birth (as abortion data were not available and early miscarriages are not well captured in hospital data). We chose the 18-month time period based on evidence that shorter birth-to-pregnancy intervals are associated with the highest risks of adverse outcomes for women and babies and after discussions with our Patient and Public Involvement (PPI) group, who felt that a second birth within 2 years was a positive event for many young mothers. 84 Nevertheless, 17% of mothers had a second child within 24 months in our cohort, compared with 21% of mothers having a repeat pregnancy within 24 months (based on inpatient data only) in the Building Blocks trial.

There are differences in the population of mothers and their social circumstances when enrolling in versions of the FNP that have been implemented in different countries. 22 These differences in underlying risks of maltreatment and in how it is detected and responded to may determine the likelihood that families might benefit from the programme in a particular setting. While there may be benefits in some settings, our findings support previous results in England of no impact on child maltreatment outcomes, and there is no evidence to suggest that benefits from the FNP will appear as children get older.

Interpretation

We found no evidence of an association between FNP and the majority of the outcomes that we evaluated. Our findings are likely to be affected by residual confounding, whereby mothers enrolled in FNP were at higher risk of adverse outcomes than those who were not enrolled, even when matching on pre-pregnancy health, education and social care characteristics. Where differences between groups were observed, interpretation of outcomes captured in administrative data is challenging and complex. 24 For example, our finding of an increased risk of unplanned admissions for injury/maltreatment in the FNP group could represent more injuries in this group but could also reflect more appropriate care-seeking, particularly for minor injuries. Family nurses encourage mothers to have their child seen by a clinician when necessary, and this is particularly likely to be apparent during the 2-year period in which family nurses are visiting families. We also saw increased rates of A&E attendances, outpatient attendances and unplanned admissions for any reason, which may represent appropriate care-seeking behaviour by parents. However, findings from the Elmira trial of the NFP showed a substantial reduction in visits to the physician for injuries or ingestions and in visits to the emergency department associated with the intervention, which, combined with other findings, was interpreted as reflecting a reduction in underlying maltreatment. 25 Therefore, the increased risk of unplanned admissions for injury/maltreatment in the FNP group in the study could genuinely represent an underlying increased risk of maltreatment. This, in turn, might be due to residual unmeasured confounding since mothers enrolled in FNP had more indicators of adversity than mothers who were not enrolled.

Our finding of weak evidence of a reduction in the number of CPPs associated with FNP (and similar directions of non-significant associations for CiN and CLA) reinforces the complexity of understanding the mechanisms underlying these outcomes. Firstly, this finding should be interpreted with some caution given the borderline p-value (0.049) in the context of evaluating a large number of outcomes. Secondly, others have argued that given the ethical, clinical and legal mandate that family nurses have to ensure that children are protected through linkages with appropriate services, increased rates of social care contacts might well be expected in mothers enrolled in the FNP, reflecting earlier and more comprehensive surveillance. 29,116 Family nurses are in a unique position to identify early problems and start processes for safeguarding, which may explain the increased rates of discharge to social services at birth. Indeed, families in the FNP arm of the Building Blocks trial had higher rates of safeguarding procedures noted in the primary care record (13.6%) than families in the usual care arm (8.0%). 99 However, the Building Blocks 2–6 trial found no evidence of surveillance bias when evaluating thresholds for referrals to social care: rates of children who needed no further assessment after being referred were similar between arms. 24 In the study, we measured CiN and CLA in school-age children, who would not have still been seen by the family nurse and who would therefore be less likely to have been affected by surveillance bias.

We observed a higher prevalence of preterm births and low birthweight babies in the FNP group compared with mothers who were not enrolled. These are important birth outcomes, as they are associated with a disproportionate amount of healthcare use (due in part to an increased risk of chronic disease), childhood mortality and poor short- and long-term health and educational outcomes. 117,118 However, the inclusion of low birthweight as one of the primary outcomes of the Building Blocks trial was questioned, as it was not an outcome that the NFP claimed to affect and not one for which previous replicated effects had been observed. 22,23 Home visiting occurs too late to be able to influence preconception health, which is an important predictor of adverse birth outcomes. 119 Indeed, there is little evidence in general for the effect of home visiting on pregnancy outcomes, including from the NFP. 43,120,121 The apparent increased risk of all-cause hospital admissions that we observed in the FNP group may therefore be influenced in part by the higher prevalence of adverse birth outcomes in this group, which are associated with increased unplanned hospital admissions in the first years of life. 122

Our finding of an association between FNP enrolment and a small increase in the number of children achieving a Good Level of Development (school readiness) at age 5 supports similar findings from the Building Blocks 2–6 trial and fewer maternally reported developmental concerns at age 2 in the FNP arm of the original Building Blocks trial. 24 The Good Level of Development is not particularly sensitive to fine changes as a measure of school readiness, and so the underlying association may be even more substantial. 123 Building Blocks 2–6 also found an effect of FNP on Key Stage 1 outcomes, which was not replicated in this study.

Evidence suggests that a large number of families who meet the criteria for FSM do not apply for the benefit. 124 Our finding that mothers enrolled in the FNP were more likely to have children registered for FSM may therefore indicate that family nurses are able to help mothers access the support that is available to them (which includes needing to claim the underlying welfare benefits that form the basis for FSM eligibility) and to overcome recognised barriers such as inadequate information about the claiming process. FSM eligibility is a robust indicator of social disadvantage, and we show that almost half of children born to adolescent mothers are registered (compared with 14% of children nationally who were in school in 2015–6). 125,126 Given the associations between socioeconomic disadvantage, adolescent motherhood and adverse child outcomes, strategies to address the root causes of social disadvantage are also required in order to reduce inequalities and improve outcomes for mothers and their children.

Despite controlling for higher rates of pre-pregnancy unplanned admissions to hospital for diagnoses relating to adversity (substance misuse, self-harm or violence) or mental health conditions in mothers enrolled in FNP, we found that this group continued to have higher rates of these admissions, and A&E attendances, in the 2 and 7 years after giving birth. Part of this may be due to increased self-reflection and self-efficacy as a result of the programme: family nurses work with mothers to explore the trauma that many of them have experienced in the past and to become more insightful about their own needs. Cuts to mental health services have made making appropriate referrals difficult, which may lead to mothers ending up in A&E. We could only measure the most severe problems, as we only identified cases that resulted in a hospital admission record. We did not have data on primary care, which could have provided more information on outcomes that were not severe enough to result in a hospital admission. In our cohort as a whole, 6% of mothers had an unplanned admission to hospital for adversity-related diagnoses, and 8% of mothers had an unplanned admission for mental health-related diagnoses in the 7 years following delivery. Capturing measures of domestic violence is challenging, as mothers may choose not to report violence for fear that a child may be taken away or only make disclosures after a trusting relationship is built with their family nurse or health visitor. 108–110 We are therefore likely to have underestimated the extent of these conditions, meaning that there are many more mothers who are in need of continued support for their health after birth. Others have argued the importance of taking a long-term view of the health of vulnerable mothers, and our findings highlight that vulnerable mothers as well as their children continue to need support for many years after giving birth. 127

Of the younger mothers in our cohort who had not completed their education before becoming pregnant, 10% were able to go on to achieve 5 A*–C grades at GCSE level. While these rates are lower than national figures (around 60%), this still represents a substantial achievement for young mothers who are balancing the responsibilities of caring for a new baby and studying for their exams. However, these findings highlight the structural barriers and challenges that adolescent mothers will face as they become young adults and move into the world of employment. More needs to be done to halt this cycle of poverty and income inequality and to improve the life chances of young mothers. 5

Our finding of a reduction in the number of subsequent deliveries within 18 months should be interpreted cautiously. As we could not measure abortions or miscarriages in this study, we do not know how many mothers in each group became pregnant but chose, or were unable, to continue their pregnancy. However, birth spacing is key for both promoting maternal education and engagement in the workforce and preventing harm to the mother and child, and we show that it may be possible for the programme to influence birth spacing and therefore the maternal life course. This is an important finding: national surveys in England have shown that only 12% of pregnancies in mothers aged 16–19 are planned, highlighting the need for primary prevention strategies to avoid unwanted pregnancies. 128 Previous research has also shown that the effects of adolescent motherhood persist for previous adolescent mothers giving birth again in their 20s, meaning that strategies to improve the life changes of reproductive choices for young women about the timing of their pregnancies could have lasting effects. 12

Summary of main results and comparison with previous evidence

Overall, 58% of mothers enrolled in the FNP giving birth between April 2010 and January 2018 completed the programme, and 42% left early. Compared with targets, attrition was slightly lower in pregnancy (8%) but higher in infancy (23%) and toddlerhood (19%). These attrition rates are also higher than were observed in the Building Blocks trial (4% in pregnancy, 10% in infancy and 8% in toddlerhood), possibly reflecting a trial effect whereby FNP nurses involved in the trial might have felt more expectation to retain mothers in the programme. Alternatively, this could reflect changes in practice over time and increased flexibility in recent years, allowing mothers to leave the programme early.

The mean number of visits received by mothers across the programme was 36 (median 38). This is similar to that reported in Building Blocks (mean = 39 visits). Across the programme stages, the median number of visits was 10 in pregnancy, 10 in infancy and 14 in toddlerhood, compared with 10, 19 and 13, respectively, in Building Blocks. Overall, mothers enrolled in FNP received an average of 42 hours of contact time with a family nurse throughout the programme.

Approximately 60% of mothers met the fidelity targets for the number of completed visits in pregnancy, 65% in infancy and 60% in toddlerhood. This was slightly higher than fidelity targets reported in the Buildings Blocks trial, which reported 58% in pregnancy, 53% in infancy and 44% in toddlerhood. This may be due to differences in the way that the expected number of visits was calculated in each study, taking into account the time period in which a mother was enrolled (and therefore the number of visits for which she could possibly receive).

Overall, only 28% of mothers met the fidelity targets across all stages of the programme. This could reflect an unrealistic time commitment for mothers or practical problems in arranging visits to suit both mothers and nurses (who have maximum caseloads of 25 mothers). Following the publication of the Building Blocks trial and qualitative research suggesting that mothers wanted more flexibility within the programme, the FNP National Unit made the decision to allow greater flexibility in the appropriate number of visits per mother, which is now decided locally (‘dialling up’ or ‘dialling down’ according to a nurse-client assessment of need), along with the optimal time for graduation. 129,130 It is not yet clear how these recent changes to the programme will impact longer-term outcomes: more information on why a mother leaves the programme is needed to evaluate these changes.

We show that the most vulnerable and youngest mothers tended to have greater numbers of visits and were more likely to meet the fidelity targets than those who did not have these risk factors. After adjusting for these characteristics, mothers who met the target for the number of expected visits in pregnancy were less likely to have a subsequent birth within 18 months than those who did not meet the target; children born to mothers who met the target in infancy and toddlerhood were more likely to have unplanned hospital admissions for maltreatment/injury up to age 2 than those who did not meet the targets in these stages.

Interpretation

Our finding that the most vulnerable and youngest mothers received a greater dosage of visits and were more likely to meet fidelity targets than those who did not have these risk factors suggests that even before the introduction of the Accelerated Design and Programme Testing (ADAPT) sites, family nurses were making decisions about where to prioritise their time and resources and were able to provide more intensive support to those they felt most needed it. These findings make evaluating the impact of dosage of the FNP problematic since the most vulnerable mothers receive more visits but are also independently more likely to experience worse outcomes. However, our findings for unplanned hospital admissions for maltreatment/injury and subsequent births mirror those of Objective 2 comparing mothers enrolled or not enrolled in FNP: mothers who had more visits were more likely to have children with unplanned hospital admissions for maltreatment/injury up to age 2 but less likely to have a subsequent pregnancy within 18 months. For a Good Level of Development and maternal hospital admissions, we found no evidence of a difference in outcomes for mothers who met the fidelity targets and those who did not. An experimental design, combined with more detailed information on why mothers leave the programme, could be used to further evaluate the impact of the number of visits on outcomes. This may be especially relevant in the context of limited resources and previous evidence suggesting that ‘less is more’ for interventions aiming to enhance parental sensitivity and promote attachment. 131

Findings from the qualitative analysis emphasise that the length of the programme is important to both mothers and Family Nurses (Box 2).

Strengths

A major strength of this study was the use of a population-based cohort of all first-time adolescent mothers giving birth in English NHS hospitals, linked to routine education and social care records. This provided us with a large sample size for analysing subgroups and increased statistical power for detecting small differences. Linking 99% of FNP mothers to HES gave us a highly generalisable cohort of FNP mothers enrolled between April 2010 and March 2019. Using propensity scores derived from observed data on maternal histories recorded in health, education and social care data, we were able to create closely matched groups for > 95% of the FNP mothers in our cohort. The unmatched mothers were captured in a sensitivity analysis using matching with replacement and in the multivariable regression analysis.

Another strength was our use of objective measures of indicators of maltreatment and child development. However, these blunt measures could be supplemented by multimethod approaches in order to give a more nuanced interpretation of outcomes, as is being done for the evaluation of the German Pro Kind intervention, which will use a combination of interviews, observations and administrative data. 132 We also spent a significant amount of time talking to FNP teams, including observing a home visit, in order to understand the perspectives of family nurses and the mothers and families they represent. This enhanced our ability to interpret the results we observed in the data.

Limitations

The potential sources of bias and the steps we took to try to minimise these are summarised in Table 18 and the following sections.

Delivering interventions to high-risk families

To reduce social inequalities, effective interventions need to be available to all those who meet eligibility criteria. In 2010–7, most adolescent mothers at the highest risk of adverse outcomes were not receiving FNP, and we have few data on the support that they did receive during and after pregnancy. Eligible adolescent mothers living in areas with many births to adolescent mothers were least likely to receive FNP support. Moreover, adolescent mothers with similar vulnerabilities in areas where FNP was not commissioned were unlikely to have had access to equivalent intensive support. Our recommendations for delivering interventions to high-risk families are:

• Commissioning of interventions to adolescent mothers should aim to provide adequate support to meet the needs of all adolescent mothers (not just a subset of them) through increased provision of intensive services in line with local needs and the availability of other local services. For example, commissioning could be linked to the expected number of adolescents giving birth in an area; local priorities and other factors influencing local commissioning should be routinely recorded so that different commissioning strategies can be evaluated.

• Information about the maternal characteristics associated with outcomes should inform targeting in the context of insufficient commissioning of the programme.

• Other groups of mothers who have been shown to be at equally high risk for adverse child outcomes to adolescent mothers, such as those living in deprived areas and those with a history of unplanned hospital admissions for adversity or mental health conditions, should also be considered for intensive support (as they are in FNP ADAPT sites). 60,89

• Decisions about the appropriate level of care for each family (including ‘dialling up and dialling down’ the intensity of support) should be based on continuous evaluations of who is most likely to benefit, supported by a more complete recording of vulnerabilities antenatally and real-time linkage of routine health and social care data. 89,153 This could add to primary prevention strategies aiming to improve reproductive choices for women about the timing of their pregnancies.

Improving data to support quasi-experimental research studies

There remains uncertainty about whether intensive home visiting is effective for reducing child maltreatment because of the potential for bias relating to the selection of the most vulnerable mothers into FNP on the basis of unmeasured characteristics (which could mask beneficial effects) and the lack of information about usual care for adolescent mothers not enrolled in FNP (which could introduce bias to the null). Understanding variations in usual care provision among both mothers enrolled in FNP and controls is also necessary to better estimate the incremental effect of FNP and account for any unexpected variation in usual care during the evaluation period. Such information would allow more nuanced interpretation of results, including, for example, if the programme worked better in one local area than another. Our recommendations for improving the available data to support evaluations of complex interventions using administrative data are:

• More complete recording of the characteristics that are used to prioritise mothers for enrolment in each site (including start and end dates of these prioritisation characteristics) and other important maternal characteristics for adjustment purposes.

• Detailed recording of programme metadata, including site activity dates and geography and criteria being used by FNP teams in order to correctly define eligible groups of mothers who were and were not enrolled or eligible for the intervention. These programme characteristics should be available in an easily searchable central repository.

• Individual-level or aggregate data on characteristics of all mothers-to-be offered enrolment and those who declined versus those who accepted enrolment.

• Improved, high-quality data on usual care, that is, community health contacts of all eligible women at the individual level (including, e.g. public health or teenage pregnancy midwife services, number and type of health visitor contacts, number of children’s centres). These data could be captured in the Community Services Dataset, but the completeness of this data set is variable over time and across areas. 137,139

Development of the intervention

• More research is needed to understand which elements of intensive interventions are most effective, for whom and when and to help inform decisions about whether it is better to commission highly intensive services for a small portion of the target population or to extend and enhance universal services to better support all adolescent mothers. For example, research could evaluate the effectiveness of enhanced midwifery support in pregnancy delivered by specialist teenage pregnancy midwives.

• Research is needed to understand the spillover effects of the programme on non-FNP mothers. 154 While the FNP may enhance other services (e.g. as trained family nurses take on other roles) by dissemination of trauma-informed approaches and understanding of the teenage brain, qualitative data also suggest that professionals are concerned about the licensed nature of FNP and not being able to share freely with wider health visiting colleagues or use it to change practice across services. 111 We do not yet know if FNP diverts resources away from the usual care that an adolescent mother should receive or if there are any other unintended harms of the programme. 155

• There is ongoing work in the ADAPT sites to tailor the programme more closely to individual mothers and families. Further robust evaluation is needed of modifications to the FNP, including the changes included in the ADAPT sites and including outcomes for mothers aged 20–24 (who we could not assess in this study due to small numbers enrolled with sufficient follow-up).

• Better understanding is needed of how the programme and outcomes are affected by different modes of delivery, such as those that were implemented during the COVID-19 lockdown. 156 An evaluation of the FNP during lockdown in Scotland found that all survey respondents reported continuing home visits during lockdown, though some mothers were not comfortable receiving home visits. Mothers reported invaluable support and felt their family nurses provided stability, advice and care, particularly those who became socially isolated.

Improvement of delivery, including targeting

• Research is needed to find ways to support achieving continuity of care and to support learning and wider sharing with health visiting colleagues, which would allow FNP to change practice across the service.

• Availability of more accurate individual- or household-level deprivation measures (including those available through Unique Property Reference Numbers) would improve our ability to create closely matched groups, provide enhanced information on the social support available within a household and help more effective targeting and follow-up of the many young mothers experiencing socioeconomic disadvantage. 157

Measuring the right outcomes

• We have reported initial findings from a qualitative study of the experiences of parents and practitioners involved in FNP, and further findings from this work will inform our understanding of the mechanisms of effect of FNP and for which outcomes we are most likely to see effects. This is particularly important in the context of quasi-experimental research studies, where bias and/or data limitations are likely to influence findings.

• Better measures of changes from enrolment in maternally reported well-being, confidence, mental health, parent–child interaction and child behaviour would allow us to understand more nuanced effects of the programme not routinely captured in administrative data.

• Future research should also consider outcomes for fathers, who have not been considered to date in evaluations of FNP and who are hard to capture in administrative data. 158

• Research is needed to understand whether FNP can mediate outcomes for those with adverse birth conditions (e.g. preterm birth and low birthweight) and whether there are any residual (‘sleeper’) effects for subsequent children.

• More research is needed to understand whether the FNP has an effect on mortality for mothers and children, rates of abortions and the reasons for hospital admissions, including malnutrition.

• Future studies should quantify the total costs of FNP compared to usual care, including non-contact time of family nurses and additional resources used by FNP mothers and their children.

Design of future studies

• A randomised controlled trial is needed to further evaluate the impact of the number of FNP visits or contacts on outcomes, including self-reported outcomes and other measures of child development, for example, Language Environment Analysis (LENA). 159 As a trial will also have its challenges, including attrition, recruitment and standardisation of usual care, experimental designs should also have a strong qualitative component to extend the contextual explanation of variation, for example, across localities.

• Other ways to analyse the data and avoid excluding high-risk mothers from analysis could be explored, for example, using target trial emulation. 160

• Linkage to primary care and the Maternity Services Dataset could enable investigation of a wider range of risk factors.

• Routine linkage of education, social care and health data should be used to enable more efficient evaluations of early interventions. 161 Some organisations have called for the collection of a unique identifier in data for all children’s services to enable services to work in a more joined-up way, which could be used to facilitate research in the future. 162,163

Linking mothers and babies in the study cohort to National Pupil Database