Aagaard K, et al. - The relationship between head circumference at birth, a measure of cerebral size at birth, and the risk of Attention Deficit Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) was investigated in this analysis. Between 1997 and 2013, a register-based cohort study of all Danish singletons born alive was presented. This study comprised 986,909 new-borns. The authors discovered that smaller head circumference at birth was linked with a higher risk of ADHD within normocephalic children. Risk factor for the development of ADHD could be a restricted foetal brain growth but not ASD.