Fetal sex influences maternal fasting plasma glucose levels and basal β-cell function in pregnant women with normal glucose tolerance

Aims: Fetal sex has recently emerged as a new factor that is related to maternal glucose homeostasis during pregnancy. The present study aimed to investigate the effect of fetal sex on maternal glucose metabolism in women with normal glucose tolerance (NGT) during pregnancy in the Chinese population.

Methods: A total of 877 pregnant women with NGT were recruited at 24-28 weeks of gestation and underwent a 75-g oral glucose tolerance test (OGTT). Pregnant women were divided into two groups according to fetal sex. Physical examinations and laboratory tests were performed. Pancreatic β-cell function and insulin sensitivity were evaluated using OGTT-derived indices.

Results: Compared with women bearing female fetuses, women who delivered male fetuses had higher fasting plasma glucose (FPG) concentrations [4.5 (4.2-4.8) vs. 4.4 (4.2-4.7) mmol/L, P < 0.05], but lower HOMA-β [161.9 (118.2-238.8) vs. 181.0 (131.7-260.9), P < 0.05] and Stumvoll first phase of insulin secretion [1230.2 (1077.9-1433.7) vs. 1290.9 (1134.0-1493.2), P < 0.05]. Multiple linear regression analysis indicated that the sex of the fetus was independently associated with maternal FPG and HOMA-β. Further binary logistic regression analyses revealed that the presence of a male fetus was significantly associated with elevated FPG [odds ratio (OR) 1.50; 95% confidence interval (CI) 1.12-2.00; P = 0.006] and lower HOMA-β (OR 0.70; 95% CI 0.52-0.94; P = 0.018) even after adjustment for potential confounders.

Conclusions: This study provided evidence that maternal glucose metabolism could be affected by fetal sex even in NGT pregnant women. Our results suggest that the presence of male fetuses was independently associated with maternal elevated FPG and lower basal β-cell function.