Advances in obstetric care have been accompanied by increasing rates of intervention which often involve elective delivery at 37 weeks, soon after term gestation has been achieved.

The aim of this study was to examine the behavioural sequelae for children born at this early term gestational age compared with those born at later weeks.

The Western Australian Pregnancy Cohort (Raine) Study provided comprehensive obstetric data from 2900 pregnancies. Offspring were followed up at ages two, five, eight, 10, 14 and 17 years using the parent report Child Behaviour Checklist (CBCL) with clinical cutoffs for overall, internalising (withdrawn, somatic complaints, anxious/depressed) and externalising (delinquent, aggressive) behaviour (T‐score ≥ 60). We used longitudinal logistic regression models incorporating generalised estimating equations (GEE) with step‐wise adjustment for ante‐, peri‐ and postnatal confounding factors.

Approximately 9% of our cohort was born within the range of 370/7 and 376/7 weeks. Those born at 37 weeks’ gestation were at increased risk for overall (OR = 1.43, 95% CI = 1.02, 2.01) and externalising (OR = 1.42, 95% CI = 1.01, 2.01) behavioural problems in the fully adjusted model when compared with infants born from 39 weeks onwards. Infants born late preterm (34–36 weeks) and at 38 weeks did not show a significantly increased risk for behavioural problems.

Infants born at 37 weeks’ gestation are at increased risk for behavioural problems over childhood and adolescence compared with those born later in gestation. We suggest that 37 weeks’ gestation may not be the optimal cutoff for defining perinatal risk as it applies to behavioural development.