Autism and head circumference in the first year of life.

BACKGROUND: It has been reported that children with autism and pervasive developmental disorder have a significantly smaller head circumference at birth and that their head circumference then increases disproportionately rapidly in the first year of life. METHODS: We attempted to replicate these findings using 15 narrowly defined autistic children from the National Collaborative Perinatal Project and approximately 40,000 nonautistic control subjects. RESULTS: The autistic group had a slightly but not significantly larger head circumference at birth. At 4 months, the head circumference in the autistic group was not significantly larger than that of control subjects, but body weight and length were significantly larger in the autistic group. CONCLUSIONS: We believe this is the first report of significant general body growth in autistic children in infancy; the larger head circumference may be part of this excessive general growth.