Gestational diabetes in the United States: temporal trends 1989 through 2004.

OBJECTIVE: The objective of the study was to characterize trends in gestational diabetes (GDM) by maternal age, race, and geographic region in the United States.

STUDY DESIGN: The National Hospital Discharge Survey, comprised of births in the United States between 1989 and 2004 (weighted n = 58,922,266), was used to examine trends in GDM, based on an International Classification of Diseases, Ninth Revision, Clinical Modification code of 648.8. We examined temporal trends by comparing GDM rates in the earliest (1989-1990) vs most recent (2003-2004) biennial periods. Relative risks, quantifying racial disparity (black vs white) in GDM, were derived through logistic regression models after adjusting for confounders. These analyses were further stratified by maternal age and geographic region.

RESULTS: Prevalence rates of GDM increased from 1.9% in 1989-1990 to 4.2% in 2003-2004, a relative increase of 122% (95% confidence interval [CI] 120%, 124%). Among whites, GDM increased from 2.2% in 1989-1990 to 4.2% in 2003-2004 (relative increase of 94% [95% CI 91%, 96%]), and this was largely driven by an increase in the 25-34 year age group. In contrast, the largest relative increase in GDM (260% [95% CI 243%, 279%]) among blacks between 1989-1990 (0.6%) and 2003-2004 (2.1%) occurred to women aged younger than 25 years. The black-white disparity in GDM rates widened markedly among women aged younger than 35 years in the 1997-2004 periods. The largest relative increases were seen in the West (182% [95% CI 177%, 187%]) followed by the South and Northeast. The observed increase in GDM rates in the Northeast, Midwest, and South regions most likely is due to increase in GDM prevalence rates among blacks.

CONCLUSION: This study shows that the prevalence rate of GDM in the United States has increased dramatically between 1989 and 2004. The temporal increase and the widening black-white disparity in the rate of GDM deserves further investigation.