Sex Differences in the Incidence of Neonatal Abnormalities and Abnormal Performance in Early Childhood

Data from the Collaborative Study of Cerebral Palsy were analyzed for sex differences in physical, psychological, and neurological development from birth to 4 years of age. Significant sex differences, showing the male to be at a disadvantage, were found in performance on all scales. The possibility that these differences in performance were related to neonatal experience was supported by the finding of significant sex differences in neonatal condition. Males, although they have the advantage of higher birthweight, do less well than females from birth through 4 years of age. Although these sex differences must have a basic genetic origin, it was suggested that such factors as obstetrical problems, neonatal distress, and maternal attitudes may have a mediating effect. Possible etiologic mechanisms were discussed.