Aims and Hypothesis: Women carrying a male fetus are suggested to have altered maternal glucose and insulin dynamics and increased rates of GDM, but current literature remains inconclusive. We aimed to determine the relationship between fetal sex and maternal glucose and insulin metabolism and assess whether inclusion of fetal sex improves prediction of IADPSG GDM.

Methods: Using blinded data from five Hyperglycaemia and Adverse Pregnancy Outcome study centres, we examined maternal metabolic data at mean gestational week 28 in 6337 untreated women. Stratifying women by either male (n = 3273) or female fetus (n = 3064) we analysed data from the 75g OGTT, estimates of insulin secretion (Stumvoll first phase) and sensitivity (Matsuda index) and their product (oral Disposition index) using multiple linear regression analysis. To assess the relationship and predictive ability of fetal sex and GDM we utilised multiple logistic regression and receiver operating characteristic curve analysis.

Results: Women carrying a male fetus were found to have a modest increase in fasting plasma glucose (4.52 vs. 4.44 mmol/L; P=0.008) and 1 h glucose (7.57 vs. 7.46 mmol/L; P=0.015) during OGTT which translated into an overall increase in the OGTT z score (0.vs. 0.02; P=0.005) . The Matsuda (β: -0.06; 95% CI [-0.10, -0.02]; P=0.008) and oral Disposition index (β: -0.07; 95% CI [-0.11, -0.02]; P=0.005) were significantly reduced in women carrying a male fetus after correction for established maternal clinical risk factors. Women carrying a male fetus were not at higher odds of developing GDM in adjusted (aOR: 1.04; 95% CI [0.9, 1.19]; P=0.6) or unadjusted (OR: 1.09; 95% CI [0.96, 1.25]; P=0.16) models.

Conclusion/interpretation: The male fetus is associated with increased maternal fasting and postprandial glucose with concomitant decreased insulin sensitivity and β-cell compensation. The alterations in maternal glucose and insulin dynamics associated with having a male fetus does not translate into a clinical diagnosis of GDM.


T.P.Mullins: None. K.S.Gibbons: None. L.R.Madsen: None. R.C.Ma: Other Relationship; Bayer AG, Boehringer Ingelheim International GmbH, Research Support; AstraZeneca, Bayer AG, Novo Nordisk A/S, Pfizer Inc., Tricida, Inc. W.H.Tam: None. P.Catalano: None. D.A.Sacks: None. H.L.Barrett: None. D.Mcintyre: None.

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