Keywords:
Autism Spectrum Disorder/diagnosis/epidemiology; Autistic Disorder; Birth Order; Phenotype; prospective Studies; Autism spectrum disorder; diagnosis; first birth; intellectual disability
Abstract:
Birth order effects have been linked to variability in intelligence, educational attainment and sexual orientation. First- and later-born children have been linked to an increased likelihood of an Autism Spectrum Disorder (ASD) diagnosis, with a smaller body of evidence implicating decreases in cognitive functioning with increased birth order.