Mild prematurity, proximal social processes, and development.

Objective: To elucidate the role of gestational age in determining the risk of poor developmental outcomes among children born late preterm (34-36 weeks) and early term (37-38 weeks) versus full term (39-41 weeks) by examining the contribution of gestational age to these outcomes in the context of proximal social processes.

Methods: This was an analysis of the Canadian National Longitudinal Survey of Children and Youth. Developmental outcomes were examined at 2 to 3 (N= 15099) and 4 to 5 years (N= 12302). The sample included singletons, delivered at 34 to 41 weeks, whose respondents were their biological mothers. Multivariable modified Poisson regression was used to directly estimate adjusted relative risks (aRRs). We assessed the role of parenting by using moderation analyses.

Results: In unadjusted analyses, children born late preterm appeared to have greater risk for developmental delay (relative risk = 1.26; 95% confidence interval [CI], 1.01 to 1.56) versus full term. In adjusted analyses, results were nonsignificant at 2 to 3 years (late preterm aRR = 1.13; 95% CI, 0.90 to 1.42; early term aRR = 1.11; 95% CI, 0.96 to 1.27) and 4 to 5 years (late preterm aRR = 1.06; 95% CI, 0.79 to 1.43; early term aRR = 1.03; 95% CI, 0.85 to 1.25). Parenting did not modify the effect of gestational age but was a strong predictor of poor developmental outcomes.

Conclusions: Our findings show that, closer to full term, social factors (not gestational age) may be the most important influences on development.