Neonatal unit admission and offspring mental health trajectories across childhood and adolescence: a nationally representative UK cohort study.

Objective: To investigate the associations between neonatal unit admission (NNU) and subsequent emotional and behavioural difficulties during childhood and adolescence.

Design: Longitudinal general population cohort study.

Setting: The Millennium Cohort Study: nationally representative UK-based cohort.

Participants: All children with exposure, outcome and confounding data.

Exposure: NNU admission was identified at 9 months by asking parents whether their baby was 'taken to special care or neonatal or intensive care unit after birth'.

Main outcome measures: Emotional and behavioural problems were assessed using the Strengths and Difficulties Questionnaire when children were 3, 5, 7, 11, 14 and 17 years. We explored the association between NNU admission and trajectories of emotional and behavioural problems using multilevel models with growth curves for outcome data between 3-17 years and adjusted for a broad range of confounders.

Results: 14 013 participants (48.9% female, 13.7% ethnic minority) were included in the analytical sample. In the sample, mean gestational age was 275.81 (SD): 13.80) days, and mean birth weight was 3.36 kg (SD=0.58). 1273 (9.1%) participants had an NNU admission. The latter was associated with increased emotional difficulties (mean difference (MD) 0.13, 95% CI 0.045 to 0.22, p=0.003) and peer problems (MD 0.11, 95% CI 0.026 to 0.19, p=0.010) during childhood in fully adjusted models. There was no evidence that NNU admission was associated with conduct problems (MD 0.013, 95% CI -0.062 to 0.088, p=0.732) or hyperactivity symptoms (MD 0.042, 95% CI -0.070 to 0.15, p=0.452).

Conclusions: Children admitted to NNUs at birth are more likely to experience emotional difficulties and peer problems during childhood. These differences are apparent from early childhood continuing into adolescence and strengthen the case for a calm NNU environment with parental visits and mental health support, and early interventions for children admitted to NNUs.