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The role of male foetal sex on maternal and neonatal outcomes in pregnancies complicated by gestational diabetes-secondary analysis of a randomised placebo controlled clinical trial of metformin in gestational diabetes (EMERGE)

Newman C, Alvarez-Iglesias A, Eyers K, McEvoy RP, O'Shea PM, Gillespie P, Devane D, Egan AM et al.

BMC medicine, 2026

1 citation

Abstract

Background Male foetal sex is recognised as an independent risk factor for adverse pregnancy outcomes including preterm birth, neonatal care unit admission and lower Apgar scores. Male foetuses appear to increase the risk of maternal gestational diabetes in the mother due to impacts on beta cell function, and in pregnancies impacted by gestational diabetes, male offspring have higher rates of hypoglycaemia, respiratory distress and macrosomia. Metformin exposure in animal models has also demonstrated sex-specific effects with different patterns in adiposity and lipid levels observed between male and female offspring exposed to metformin in utero. The aim of this analysis is to determine whether foetal sex modifies maternal and neonatal outcomes in gestational diabetes, and evaluate the sex-specific response to metformin on insulin usage, fasting glucose at 32 and 38 weeks and foetal size. Methods We conducted a secondary analysis of the Early Metformin in Gestational Diabetes (EMERGE) randomised controlled trial and analysed neonatal outcomes according to sex and metformin exposure. Results At randomisation, women carrying a male foetus had a higher plasma glucose at 60 min on oral glucose tolerance testing (9.69 vs. 9.37 mmol/L, p = 0.039). In exploratory analyses, metformin exposure in male pregnancies was associated with lower fasting glucose at 32 (4.88 vs. 5.01 mmol/L, p = 0.014) and 38 weeks (4.49 vs. 4.69 mmol/L, p = 0.002) and reduced insulin use (38% vs. 53%, p =…

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Evidence Hub reads this as a secondary / pooled analysis, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence.

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