Autism risk in small- and large-for-gestational-age infants.

The authors sought to determine whether small-for-gestational age (SGA) and large-for-gestational age (LGA) birthweights increase autism risk. : This was a retrospective cohort analysis comparing children with autism (n = 20,206) within a birth cohort (n = 5,979,605). Stratification by sex and birthweight percentile (SGA, 10th to 95th percentile) preceded Cochran-Mantel-Haenszel analysis for GA effect, and multivariate analysis. Autism risk was increased in preterm SGA (95th percentile) infants 39-41 weeks (aOR, 1.16; 95% CI, 1.08-1.26), but was decreased in preterm LGA infants 23-31 weeks (aOR, 0.45; 95% CI, 0.21-0.95). CONCLUSION: SGA was associated with autism in preterm infants, while LGA demonstrated dichotomous risk by GA, with increased risk at term, and decreased risk in the premature infants. These findings likely reflect disparate pathophysiologies, and should influence prenatal counseling, pediatric autism screening, and further autism research.