Intensive home visiting for adolescent mothers in the Family Nurse Partnership in England 2010–2019: a population-based data linkage cohort study using propensity score matching

Introduction

Each year, approximately 3% of babies (~16 000 in 2020) are born to mothers aged less than 20 years in England and Wales.1 Adolescent mothers are more likely to experience adversity, be less engaged with education and employment, and have rapid repeat pregnancies compared with older mothers.2–5 For their children, young maternal age is associated with higher incidence of preterm birth and low birth weight,6 7 and a greater risk of child maltreatment and associated adverse long-term consequences including poorer physical health, social, emotional and cognitive outcomes.8–10 These adverse maternal and child outcomes of adolescent pregnancy, associated with social adversity, disruption to education and employment, and child-rearing practices, are of major importance to public health research and the National Health Service (NHS).11 12 Understanding how best to target services to the most vulnerable mothers is key to improving health for these mothers and their children.

Many intensive health services aiming to reduce maltreatment and/or inequalities between adolescent and older mothers have been trialled. While some meta-analyses have found positive effects across a range of child and parent outcomes including maltreatment,13–15 others have found a more ‘gloomy’ picture,16 in part due to the effectiveness of different components of these programmes for different outcomes.17 18 One programme consistently recognised for its effects is the Family Nurse Partnership (FNP),19 which is currently the only programme recommended within the UK government Healthy Child Programme, and which has been commissioned in >130 English Local Authorities since 2007. Mothers enrolled in the FNP receive up to 64 home visits by a dedicated family nurse, from early pregnancy until the child’s second birthday. The FNP aims to improve birth outcomes, child health and development, and to promote economic self-sufficiency among young mothers.20

Most of the evidence of effectiveness of the FNP stems from three randomised trials of the Nurse-Family Partnership (NFP) conducted in the USA, which evaluated a wide range of maternal and child outcomes, with up to 20 years of follow-up. The three USA trials showed mixed but overall positive impacts on child health and development outcomes, and on some maternal outcomes. A more recent Netherlands randomised controlled trial (VoorZorg, enrolling in 2007–2009) also reported a reduction in child abuse/maltreatment reports by age 3 years in the FNP arm. These results contrast with a more recent trial of 5670 Medicaid-eligible nulliparous pregnant mothers recruited between 2016 and 2020 in South Carolina, which found no evidence of an effect on birth outcomes (preterm birth, low birth weight, small for gestational age and perinatal death), and the Building Blocks trial of FNP in England (enrolling approximately 1600 expectant mothers in 2009–2010), which showed no evidence of impact of FNP on most child outcomes, with the exception of some cognitive outcomes including maternally reported child cognitive and language development in the first 2 years of life, and a good level of development at school entry (a measure of school readiness at age 5 years).21

Historically, FNP has been delivered in a similar way in England as the NFP is delivered in the USA (although more flexibility has been introduced in recent years).22 The licensing agreement stipulated that sites should follow a number of core model elements, so that the FNP could be replicated consistently, in order for the conditions upon which the previous evidence from the USA were based to be replicated. However, there are notable differences in eligibility criteria. Therefore, two potential explanations for different results in England compared with the USA are variation in usual care and in eligibility. First, 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 healthcare 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. Second, the main eligibility criterion for enrolment in FNP in England is maternal age: adolescents who are aged up to 19 years at last menstrual period and who are first-time mothers are eligible for enrolment. In contrast, additional socioeconomic criteria such as unemployment, low educational level or low income are used in combination with maternal age in other countries. As a result, the population of young mothers enrolled in trials in other countries is a more selected and vulnerable group than in England, and may therefore stand to benefit more from the FNP (as evidenced by greater effectiveness in socioeconomically deprived groups demonstrated in the US trials).

Despite the results of the Building Blocks trial, there remains strong support for the programme locally.20 23–25 Around one in four eligible mothers are enrolled in the FNP within Local Authorities that offer the programme; mothers who are not offered the FNP, or who decline, are offered usual care for adolescent mothers, which varies locally.26 27 Generating evidence on which groups of mothers and their children benefit from the real-world implementation of the FNP in England is therefore needed to help inform targeting and commissioning of services, especially in the context of findings from the US trials which suggest that the youngest, most disadvantaged mothers are likely to benefit most from FNP.24 This evidence is being called for by service providers who need to understand the value of interventions in the context of their target populations and local services, in order to inform commissioning and justify spending.28 Furthermore, usual care available to adolescent mothers is likely to have declined between the Building Blocks trial study period and after the introduction of austerity measures in England—in particular, health visitor budgets have decreased since responsibility for commissioning of health visiting services shifted from the NHS to local government in England in 2015.29

Linkage of existing administrative records provides a cost-efficient means of evaluating services as they are implemented in the real world, overcoming some of the constraints of randomised trials.30 Our population-based study used longitudinal linked observational data between the health, education and social care sectors for all mothers enrolled in the FNP in England since 2010, to evaluate the effects of the intervention on outcomes of eligible mothers and their children up to age 7 years. We aimed to generate evidence on which groups of mothers and children benefit from the real-world implementation of FNP in England in order to inform the targeting and commissioning of services.

Methods

Results

Propensity score-matched cohort

FNP mothers tended to have higher propensity scores (median=0.39) than non-FNP mothers (median=0.31), meaning that these mothers had more risk factors for enrolment than those not enrolled. However, there was a good overlap of propensity scores between groups (online supplemental figure 2): we were able to include 94.9% of mothers in the matched analysis for births between April 2010 and 2019 and 95.7% of mothers in the cohort with 2 years of follow-up, and 99.9% of mothers in the cohort with 7 years of follow-up. There were no large imbalances between matched groups (all standardised differences <0.1; online supplemental figure 3).

Indicators of child maltreatment

There was an increased risk of unplanned admissions for maltreatment/injury-related diagnoses in the 2 years following birth among children of mothers who were enrolled in the FNP compared with those who were not, in the matched cohort (figure 1 and online supplemental table 10). 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, 1.51), and a decreased risk of a child protection plan up to 7 years after birth (RR 0.84; 95% CI 0.71, 1.00). The median length of stay for children admitted to hospital for maltreatment/injury-related diagnoses was the same in both groups (1 day; IQR 0.5–1, where 0.5 days indicates an admission and discharge on the same day; online supplemental table 12).

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Figure 1

Indicators of child maltreatment: adjusted relative risks* and 95% CIs comparing outcomes for mothers enrolled in the FNP versus mothers who were not enrolled, for mothers aged 13–19 years and giving birth in an area in which FNP was offered at the time of pregnancy, in the propensity-matched cohort. *Relative risks are adjusted for all maternal characteristics prior to enrolment in table 2. FNP, Family Nurse Partnership.

Child health, developmental and educational outcomes

There was an increased risk of low birth weight among mothers who were enrolled in the FNP versus those who were not (figure 2 and online supplemental table 11). 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).

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Figure 2

Child health, developmental and educational outcomes: adjusted relative risks* and 95% CIs comparing mothers enrolled in the FNP versus mothers who were not enrolled, for mothers aged 13–19 years and giving birth in an area in which FNP was offered at the time of pregnancy, in the propensity-matched cohort. *Relative risks are adjusted for all maternal characteristics prior to enrolment in table 2. A&E, Accident and Emergency; FNP, Family Nurse Partnership; KS, Key Stage.

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 years (RR 1.05; 95% CI 1.00, 1.09) than those born to mothers who were not enrolled (online supplemental table 12). Children in the FNP arm were also more likely to be recorded as having FSM.

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 with those who were not enrolled (figure 3 and online supplemental table 14). However, these mothers were less likely to have a repeat birth within 18 months of the index birth (RR 0.92; 95% CI 0.88, 0.97).

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Figure 3

Maternal outcomes: adjusted relative risks∧ and 95% CIs comparing outcomes for mothers enrolled in the FNP versus mothers who were not enrolled, for mothers aged 13–19 years and giving birth in an area in which FNP was offered at the time of pregnancy, in the propensity-matched cohort. ∧Relative risks are adjusted for all maternal characteristics prior to enrolment in table 2. *Among mothers who were aged <16 years at the start of the academic year in which they reached 20 weeks’ gestation. **Among mothers who were aged <15 years at the start of the academic year in which they reached 20 weeks’ gestation. A&E, Accident and Emergency; FNP, Family Nurse Partnership; GCSE, General Certificate of Secondary Education.

Subgroup analyses

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 (online supplemental figures 4–7).

Discussion

Our population-based study of the FNP in England supports previous evidence showing no benefit of the FNP on child maltreatment outcomes, and adds to the broader literature on the effectiveness of home visiting programmes for reducing maltreatment. We observed a small increase in the number of children achieving a good level of development (school readiness) at age 5 years associated with enrolment in the FNP, supporting similar findings from the Building Blocks 2:6 trial, and fewer maternally reported developmental concerns at age 2 years in the FNP arm of the original Building Blocks trial.21 23 We also observed a reduction in the number of subsequent deliveries within 18 months for mothers enrolled in FNP. Birth spacing of more than 18 months is key for 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.43 44 However, this result should be interpreted cautiously as we could not measure abortions or miscarriages, and we do not know how many mothers in each group became pregnant but chose, or were unable, to continue their pregnancy.

A major strength of our study was the large sample size resulting from the use of a population-based cohort of all first-time adolescent mothers giving birth in English NHS hospitals between 2010 and 2019. Linking 99% of FNP mothers to HES gave us a highly generalisable cohort of FNP mothers. Another strength was our use of objective measures of indicators of maltreatment and child development. 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.

There are a number of challenges inherent to evaluations using administrative data, and findings in this report should be interpreted in the context of three main limitations.45

First, although we carefully designed and assessed the propensity score analysis strategy, our approach is subject to the assumption that conditional on the propensity score, the distribution of characteristics between groups was balanced. However, there may be residual confounding as we could only control for the fairly crude maternal risk factors associated with enrolment in FNP that are captured in administrative data. We know that mothers enrolled in the FNP had more risk factors for adverse outcomes than those who were not enrolled (table 2). Although propensity score matching has a number of limitations, it can help most where there are high levels of imbalance as in this setting.46 However, even after matching, the increased rates of low birthweight babies, babies discharged to social services and of maternal unplanned admissions post-pregnancy for adversity and mental health-related diagnoses that we observed in the FNP group indicate that there may be residual confounding and bias by indication. Additional information on other important characteristics including less severe mental health conditions, family support and risk of unstable housing would have improved our ability to overcome this confounding. Given we know that mothers enrolled in FNP had more indicators of vulnerability at enrolment than the comparison group, such residual confounding could have limited our ability to detect beneficial effects of the programme. The weak evidence for small improvements in school readiness as measured by a good level of development in the EYFSP and reductions in the number of rapid repeat pregnancies may therefore reflect larger positive effects of the programme. However, these outcomes should still be considered in the context of being the only ‘positive’ effects among the many outcomes that were evaluated and the statistical power provided by such a large sample size. These challenges are relevant to other studies aiming to use administrative data to evaluate public health interventions.45

Second, outcomes captured in administrative data can be difficult to interpret. For example, the increased rates of unplanned admissions and A&E attendances in the mother and child associated with FNP may be viewed as contradictory to the aims of improving child health, but may actually reflect appropriate care seeking as a result of advice and support from family nurses. The increase in unplanned admissions in the FNP group was mostly driven by short stay admissions (online supplemental table 12), indicating that mothers could have been seeking help for relatively minor conditions. In addition, babies born to mothers enrolled in the FNP were more likely to be born preterm and with low birth weight: these are health conditions which are influenced by pre-conception health, and babies with these conditions would be expected to have appropriately increased rates of hospital contacts throughout childhood. Increased rates of admissions in the mother could also be interpreted as demonstrating that family nurses can have a long-term effect on maternal healthcare-seeking behaviours. 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 presenting in A&E. However, 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.

Our finding of weak evidence of a reduction in the number of child protection plans associated with FNP (and similar directions of non-significant associations for child in need (CiN) and child looked after (CLA)) reinforces the complexity of understanding the mechanisms underlying these outcomes. 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.47 48 Family nurses are in a unique position to identify early problems and to start processes for safeguarding, which may explain the increased rates of discharge to social services at birth. However, 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.

Third, FNP might have positive effects on a range of other outcomes that are not captured in administrative data. This study was not able to identify effects on changes in self-reported parental mental health, sense of self, well-being, confidence, behaviour and parent–child engagement and interaction, including for fathers. Nuances in behaviour change are difficult to measure: for example, a mother may not give up smoking completely, but may change how she smokes, by not smoking in the home and not allowing others to smoke in the home. Further work is also needed to understand how differing dose or intensity of the programme might be related to maternal characteristics and to outcomes.

Existing qualitative work demonstrates overwhelming support for the programme from mothers who have been enrolled, and from family nurses who can see the changes and impact that the intensive service has provided for the families they have worked with.49 50 However, there is a lack of conclusive systematic evidence supporting interventions for preventing child maltreatment more generally.16 51–53 Expecting to detect effects of home visiting that starts in pregnancy on birth outcomes and on relatively insensitive child development measures may also be unreasonable in the context of the social disadvantage, discrimination and other challenges that adolescent mothers face before, during and after pregnancy.54 Indeed, a 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 birth weight, small for gestational age and perinatal death).55 Strategies to address the root causes of social disadvantage experienced by young mothers are therefore also needed.

Despite reductions in adolescent pregnancies over recent decades, there remains a significant population of young and vulnerable mothers in England who need intensive support. Currently, the majority of these mothers are not receiving support from FNP, as it is not offered in all areas, and only offered to around one in four mothers in areas in which it is commissioned.26 There is strong support for FNP locally, and FNP practitioners report that mothers participating in the programme develop more reflective parenting and awareness of their child’s needs. Without better evidence, removing support for young mothers could be harmful, especially in the context of increasing social disadvantage and widespread health visitor shortages that are already putting pressure on other services.56 More research is needed to understand which elements of intensive interventions are most effective, for whom and when, and 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.18 57