Persson M, Opdahl S, Risnes K, et al. - The complex etiology of autism spectrum disorder (ASD), a neurodevelopmental disorder characterized by persistent impairments in social communication and restricted and repetitive behaviors, remains unresolved. In view of the reported link between length of gestation, including preterm birth, and the risk of ASD, researchers sought to provide a detailed and robust description of ASD risk across the entire range of gestational age (GA) while taking fetal gender and size at birth into account. They used population-based data from national medical registries in three Nordic countries (Sweden, Finland, and Norway) and identified 3,526,174 singletons born from1995 to 2015 for inclusion in this study. Log binominal regression was done to determine relative risks (RRs) of ASD by GA at birth. Increase in the RR of ASD was noted by each week of GA, pre- as well as postterm, from 40 to 24 weeks of gestation and from 40 to 44 weeks of gestation; this increase was noted independent of gender and birth weight for GA.