Objective: To assess behavioral outcomes and social competence at 2 years of age in infants born late and moderately preterm (LMPT; 32-36 wk gestation).
Method: One thousand one hundred and thirty LMPT infants and 1255 term-born (≥37 wk) controls were recruited at birth to a prospective geographical population-based study. Parents completed the Brief Infant and Toddler Social Emotional Assessment (BITSEA) at 2 years corrected age to assess infants' behavior problems and social competence. Cognitive development was assessed using the Parent Report of Children's Abilities-Revised. Parent questionnaires at 2 years were completed for 638 (57%) LMPT and 765 (62%) term-born infants. Group differences in the prevalence of behavior problems and delayed social competence between LMPT infants and term-born controls were adjusted for age, sex, small-for-gestational-age, socioeconomic status and cognitive impairment.
Results: Late and moderately preterm infants were at significantly increased risk of delayed social competence compared with term-born controls (26.4% vs. 18.4%; adjusted-relative risk [RR] 1.28; 95% CI, 1.03-1.58), but there was no significant group difference in the prevalence of behavior problems (21.0% vs. 17.6%; adjusted-RR 1.13, 0.89-1.42). Non-white ethnicity (RR 1.68, 1.26-2.24), medium (RR 1.60, 1.14-2.24) and high (RR 1.98, 1.41-2.75) socioeconomic risk and recreational drug use during pregnancy (RR 1.70, 1.03-2.82) were significant independent predictors of delayed social competence in LMPT infants.
Conclusion: Birth at 32 to 36 weeks of gestation confers a specific risk for delayed social competence at 2 years of age. This may be indicative of an increased risk for psychiatric disorders later in childhood.