Preterm birth may correlate weakly with risk of research-identified ASD

Research-identified autism spectrum disorder (ASD-R) appears to be more common in preterm babies, though this relationship is modified by various infant and maternal factors, a recent study has found.

Researchers performed a population-based cohort study on 7,876 children, of whom 8.6 percent were born preterm, before 37 weeks of gestation. ASD-R was identified epidemiologically, through medical and school records reviewed before 21 years of age.

Over the study period, 266 participants met the criteria for ASD-R, which developed by the median age of 6.5 years. The cumulative incidence rates of ASD-R at 5, 10, 15 and 21 years of age were 1.1 percent, 2.8 percent, 3.5 percent and 3.8 percent, respectively.

Relative to their term counterparts, children who were born preterm were significantly more likely to develop ASD-R (hazard ratio [HR], 1.64, 95 percent confidence interval [CI], 1.12–2.41).

Further stratification according to gestational age showed that CIs were wider for children born earlier: extremely preterm (HR, 2.62, 95 percent CI, 0.65–10.57) and very preterm (HR, 1.68, 95 percent CI, 0.54–5.29). Significance was only achieved in infants who were moderate-to-late preterm (HR, 1.60, 95 percent CI, 1.06–2.40).

Controlling for maternal and neonatal factors in multivariate analysis attenuated the overall correlation between preterm birth and ASD-R risk (HR, 1.42, 95 percent CI, 0.95–2.11). This was driven by the weakening of the effect of moderate-to-late preterm birth (HR, 1.42, 95 percent CI, 0.93–2.15). Extreme and very preterm birth remained nonsignificant.