Age at Menarche and Risk of Gestational Diabetes Mellitus: A Prospective Cohort Study Among 27,482 Women

To examine the association between age at menarche and risk of gestational diabetes mellitus (GDM). A prospective cohort study of 42,109 eligible pregnancies from 27,482 women in the Nurses' Health Study II. The adjusted risk ratios for GDM across the age at menarche categories (≤11, 12, 13, and ≥14 years) were 1.34 (95% CI 1.14-1.58), 1.13 (0.97-1.31), 1.11 (0.95-1.29), and 1.00 (referent; P for trend = 0.0005), respectively. Analysis of the mediating effect indicated that 42.1% (P = 0.0007) of the association was mediated through prepregnancy BMI. These findings suggested that earlier menarche was significantly associated with an increased risk of GDM. This association was largely mediated through prepregnancy excessive body adiposity.