Nagy, E., Loveland, K.A., Orvos, H. and Molnár, P. (2001) Gender-related physiological differences in human neonates and the greater vulnerability of males to developmental brain disorders. Journal of Gender-Related Medicine, 4, 41-49.

Objective: To examine whether gender-specific physiologic differences are present at birth and can be a basis for gender-specific vulnerability to developmental disorders in males. We report on three studies of male–female physiologic and structural differences in neonates and their relevance to observed differences in the incidence of developmental disorders in males.

Methods:

Study I: 56 neonates were examined for cardiac reactivity to the Moro reflex.

Study II: 863 neonates’ basic anthropometric data were examined to demonstrate gender-specific differences in body proportions as a possible basis for psychophysiologic differences.

Study III: Developmental data on 1000 one- to 26-week-old infants were analyzed for gender-specific developmental differences in rhythmic patterns of sleeping and eating.

Results:

Study I: There were gender-related differences in heart rate reactivity (male > female).

Study II: Male newborns had significantly larger head/chest proportions, suggesting that they may have a greater metabolic demand, related to brain size.

Study III: Mothers reported that infant males’ sleeping rhythm developed significantly later than females’, and that they slept for shorter periods at night.

Conclusions

Gender-related vulnerability in brain development is proposed, based on physiologic differences during a specific early sensitive period in development. This hypothesis may help to explain the overrepresentation of males reported for most developmental disorders