Gestational diabetes mellitus in Plymouth, U.K.: prevalence, seasonal variation and associated factors.

OBJECTIVE

To estimate the prevalence of and associated factors in gestational diabetes mellitus (GDM) and its seasonal variation.

STUDY DESIGN

A clinic-based, prospective, case register study was conducted from January 1996 to December 1997. A total of 4,942 consecutive Caucasian, pregnant women aged 15-46 years,free of a history of diabetes mellitus, underwent random plasma glucose screening and a 75-g, 2-hour oral glucose tolerance test in Plymouth, U.K. The mean (SD) age of the women was 28.2 (5.5) years. Women with and without GDM were compared.

RESULTS

The prevalence of GDM among the subjects was 1.8% (95% CI 1.4,2.2). The prevalence of GDM increased with the mother's age and random plasma glucose level and decreased with the duration of pregnancy. Using a stepwise binary logistic regression model, older age (relative prevalence [RP] 1.08 [95% CI 1.04, 1.12]) and higher random plasma glucose (RP 2.99 [95% CI 2.51, 3.551) were significant predictors of GDM. The monthly prevalence of GDM ranged from 2.9% (95% CI 1.5, 5.0) in June to 1.1% (95% CI 0.3,2.8) in November. The seasonal GDM rate ranged from 2.3% (95% CI 1.5, 3.2) in spring to 1.4% (95% CI 0.8, 2.3) in winter. The differences were not statistically significant for either the month (p = 0.82) or season (p = 0.41).

CONCLUSION

The prevalence (1.8%) of GDM in this representative sample of Caucasian pregnant women was lower than the 3-5% typically reported in other European and North American studies, and there was no seasonal pattern.