Lower birth weight indicates higher risk of autistic traits in discordant twin pairs

Background Autism spectrum disorder (ASD) is a neurodevelopmental disorder of complex etiology. Although strong evidence supports the causal role of genetic factors, environmental risk factors have also been implicated. This study used a co-twin–control design to investigate low birth weight as a risk factor for ASD. Method We studied a population-based sample of 3715 same-sex twin pairs participating in the Child and Adolescent Twin Study of...