Context — It has recently emerged that carrying a male fetus is associated with poorer maternal beta-cell function in pregnancy and an increased risk of gestational diabetes mellitus (GDM). Beta-cell dysfunction is the central pathophysiologic defect underlying both GDM and subsequent postpartum progression to type 2 diabetes (T2DM).
Objective — To determine whether fetal sex influences the natural history of maternal risk of diabetes after delivery and in a subsequent pregnancy.
Design — Retrospective cohort study.
Setting — Population-based administrative databases in Ontario, Canada.
Patients — All women with a singleton live-birth first pregnancy between April 2000 and March 2010 (n=642,987).
Exposure — Fetal sex (313,280 delivered a girl; 329,707 delivered a boy).
Main Outcome Measure — Development of T2DM or a second pregnancy. Glucose tolerance in each pregnancy was classified as either GDM or non-GDM.
Results — The population was followed for a median of 3.8 years. Carrying a boy yielded a higher risk of GDM in both the first pregnancy (OR=1.03, 95% CI 1.0002-1.054) and second pregnancy (OR=1.04, 38 1.01-1.08). For women with GDM in the first pregnancy, the likelihood of developing T2DM before a second pregnancy was higher if they delivered a girl (OR=1.07, 95% CI 1.01-1.12). Recurrence of GDM was not affected by fetal sex (p=0.7). However, amongst women with a non-GDM first pregnancy while carrying a girl, having a boy in their second pregnancy predicted an increased risk of GDM (OR=1.07, 42 1.01-1.14).
Conclusions — Fetal sex is a previously-unrecognized factor that is associated with maternal diabetic risk both after delivery and in a subsequent pregnancy.
View full text