Maternal Diabetes and Infant Sex Ratio.

A male bias at birth among infants born to women with GDM is widely recognized; mild hyperglycemia experienced early in pregnancy may signal favorable conditions and warrant investment in males. There are sparse data on women with pregestational diabetes, but some evidence for a female bias born to those with type 1 diabetes and severe hyperglycemia (i.e., requiring insulin). Disease-related maternal stress in these women may lead to the selective termination of male fetuses. Further examination of pregestational diabetes stands to contribute to scientific understanding of the sex ratio.