Characteristics and outcomes associated with fidelity in the Family-Nurse Partnership in England: a data linkage cohort study.

Objectives: To determine (1) which maternal and area characteristics are associated with reaching fidelity targets (the expected number of visits mothers should receive at each stage of the programme) in the Family-Nurse Partnership (FNP), and (2) whether achieving these fidelity targets affects outcomes.

Design, setting and population: Cohort study of mothers enrolled in the FNP, aged 13-19 years, giving birth between April 2010 and January 2018 in England. Mothers were linked to their Hospital Episode Statistics and National Pupil Database records.

Outcomes: We described whether mothers reached fidelity targets for each programme stage (pregnancy, infancy and toddlerhood) and explored the characteristics associated with reaching targets. We used generalised linear models to compare child and maternal outcomes between mothers who did and did not reach fidelity targets.

Results: Of the 28 155 mothers enrolled, 58% completed the programme. Fidelity targets were met by 59% of mothers in pregnancy, 65% in infancy and 61% in toddlerhood. The median number of visits was 38 (median 43 hours contact time). Younger mothers, those with a history of unplanned hospital admissions for adversity and those with social care involvement received a greater number of visits. Meeting fidelity targets was associated with a reduction in subsequent births within 18 months and an increase in the number of children with unplanned hospital admissions for maltreatment or injury up to age 2.

Conclusions: Achieving fidelity to the FNP is challenging, but family nurses are able to engage the most vulnerable mothers in the programme. More research is needed to understand whether fidelity to programme targets is a useful measure of mothers' experiences of intensive home visiting.