Association between Abnormal Fetal Head Growth and Autism Spectrum Disorder

Despite evidence for prenatal onset of abnormal head growth in children with autism spectrum disorder (ASD), fetal ultrasound studies in ASD are limited and controversial. We conducted a longitudinal matched case-sibling-control study on fetal ultrasound biometric measures from 174 ASD children, their own typically developed siblings (TDS; n=178) and other population-based typically developed children (TDP; n=176). During second trimester, ASD and TDS fetuses had significantly smaller biparietal diameter (BPD) than TDP fetuses (aOR zBPD =0.685, 95%CI=0.527-0.890 and aOR zBPD =0.587, 95%CI=0.459-0.751, respectively). Interestingly, sex had a significant effect on head growth with males having larger heads than females within and across groups. Also, males and females with ASD showed different head shapes which were inversely correlated with ASD severity across different gestation periods. Our findings suggest that abnormal fetal head growth is a familial trait of ASD, which is modulated by sex and is associated with the severity of the disorder.