Advanced maternal age is a risk factor for both early and late gestational diabetes mellitus: The Japan Environment and Children's Study

Aims: This study investigated the association between maternal age and early and late gestational diabetes mellitus (GDM). Methods: In total, 72,270 pregnant women were included in this prospective birth cohort study. Associations between maternal age and early GDM (diagnosed at <24 gestational weeks) and late GDM (diagnosed at ≥24 gestational weeks) were evaluated using a multinomial logistic regression model with possible confounding factors. The reference category was maternal age of 30–34.9 years. Results: Higher maternal age was associated with higher odds of early and late GDM (P-value for trend <0.0001 and <0.0001, respectively). The adjusted odds ratios (aORs) for early GDM with maternal age of 35–39.9 years and ≥40 were 1.399 (95% confidence interval [CI]: 1.134–1.725) and 2.494 (95% CI: 1.828–3.402), respectively. The aORs for late GDM with maternal age of 35–39 years and ≥40 were 1.603 (95% CI: 1.384–1.857) and 2.276 (95% CI: 1.798–2.881), respectively. Conclusions: Higher maternal age was associated with an increased risk of GDM regardless of when GDM was diagnosed. The association between maternal age and early GDM was similar to that between maternal age and late GDM.