A PROSPECTIVE-STUDY OF PREGRAVID DETERMINANTS OF GESTATIONAL DIABETES-MELLITUS

Context.-Gestational diabetes mellitus (GDM) affects 3% to 5% of pregn ancies. Knowledge of risk factors for GDM is needed to identify possib le preventive strategies. Objective.-To assess whether recognized dete rminants of non-insulin-dependent diabetes mellitus also may be marker s for increased risk of GDM. Design.-Prospective cohort study. Setting .-The Nurses' Health Study II, which involves female US nurses aged 25 to 42 years at entry. Participants.-The analyses included 14 613 wome n without previous GDM or other known diabetes who reported a singleto n pregnancy between 1990 and 1994. Of these women, 722 (4.9%) reported a new diagnosis of GDM. Main Outcome Measure: Self-report of GDM, val idated by medical record review in a subset. Results.-In multivariate analyses including age, pregravid body mass index (BMI), and other GDM risk factors, the risk for GDM increased significantly with increasin g maternal age (P for trend, <.01) and family history of diabetes mell itus (relative risk, 1.68; 95% confidence interval [CI], 1.39-2.04). R elative risks for GDM were 2.13 (95% CI, 1.65-2.74) for pregravid BMI of 25 to 29.9 kg/m(2) and 2.90 (95% CI, 2.15-3.91) for BMI of 30 kg/m( 2) or more (vs BMI of <20 kg/m(2)). Risk for GDM increased with greate r weight gain in early adulthood, and it also increased among nonwhite women. Pregravid current smokers had a relative risk for GDM of 1.43 (95% CI, 1.14-1.80), and pregravid vigorous exercise was associated wi th a nonsignificant reduction in GDM risk. Conclusions.-Advanced mater nal age, family history of diabetes mellitus, nonwhite ethnicity, high er BMI, weight gain in early adulthood, and cigarette smoking predict increased GDM risk. These observations may facilitate the identificati on of women at particular risk for GDM and suggest potential strategie s for reducing this risk even before a woman becomes pregnant, such as avoiding substantial weight gain and smoking.