Association Between Age at Menarche and Gestational Diabetes: A Retrospective Case–Control Study

Early menarche has been recognized as an early-life marker of metabolic vulnerability, yet its link to gestational diabetes mellitus (GDM) remains unclear. We investigated this association in a retrospective case–control study of 71 cases and 355 controls from a tertiary hospital in Mexico City. Age at menarche was evaluated both in categories and using restricted cubic splines to capture potential non-linear trends. Mediation analysis explored the contribution of pregestational body mass index (BMI) to the relationship between variables. Women who experienced menarche before age 12 had more than twice the odds of developing GDM compared with those whose menarche occurred between 12 and 15 years (adjusted OR = 2.51, 95% CI 1.40–4.50). In contrast, late menarche showed a minor, non-significant increase in risk. The spline models revealed a subtle U-shaped pattern, suggesting that both very early and delayed pubertal timing may carry metabolic disadvantages. The mediation analysis showed that pregestational BMI accounted for only a minor share of this association. Overall, the findings indicate that early pubertal onset may influence glucose regulation during pregnancy through pathways beyond adiposity, highlighting early menarche as a valuable marker for identifying women at higher risk of GDM.