A 20-Year Prospective Study of Childbearing and Incidence of Diabetes Mellitus in Young Women Controlling for Glycemia before Conception: The Coronary Artery Risk Development in Young Adults Study

Abstract

Objective: To determine whether childbearing increases the incidence of type 2 diabetes mellitus after accounting for preconception glycemia and gestational glucose intolerance.

Research Design and Methods: Prospective, biracial cohort examined up to five times from 1985-2006 in the multi-center, U.S. population-based Coronary Artery Risk Development in Young Adults Study. The analysis included 2,408 women (1,226 black, 1,182 white) who were aged 18-30 years, free of diabetes and had a fasting plasma glucose<126 mg/dl at baseline. Incident diabetes was by self-report, diabetes medication use, fasting plasma glucose>=126 mg/dl, and/or post 2-hr oral glucose load>=200 mg/dl. Time-dependent interim birth groups were 0 births, and 1+births with or without gestational diabetes mellitus (GDM) stratified by baseline parity. Complementary log-log models estimated relative hazards of incident diabetes by interim births adjusted for age, race, family history of diabetes, and baseline covariates (fasting plasma glucose, BMI, education, smoking and physical activity).

Results: Of 193 incident diabetes cases in 42,782 person-yrs (4.5 cases/1,000 person-yrs), 84 (44%) had 1+interim births. Among nulliparas at baseline, incident rates (95%CI) per 1,000 person-yrs were 3.2 (2.4-4.1) for 0 births, 2.9 (1.8-3.9) for 1+births without GDM, and 18.4 (10.9-25.9) for 1+births with GDM; adjusted relative hazards (95%CI) were 0.9 (0.6-1.4) for 1+births without GDM and 3.8 (2.2-6.6) for 1+births with GDM versus 0 births.

Conclusions: Childbearing did not elevate diabetes incidence among those with normal glucose tolerance during pregnancy (without GDM). Gestational diabetes conferred the highest risk of developing diabetes independent of family history of diabetes and preconception glycemia and obesity.