OBJECTIVES:

We calculated the percentage of gestational diabetes mellitus (GDM) attributable to overweight and obesity.

METHODS:

We analyzed 2004 through 2006 data from 7 states using the Pregnancy Risk Assessment Monitoring System linked to revised 2003 birth certificate information. We used logistic regression to estimate the magnitude of the association between prepregnancy body mass index (BMI) and GDM and calculated the percentage of GDM attributable to overweight and obesity.

RESULTS:

GDM prevalence rates by BMI category were as follows: underweight (13-18.4 kg/m(2)), 0.7%; normal weight (18.5-24.9 kg/m(2)), 2.3%; overweight (25-29.9 kg/m(2)), 4.8%; obese (30-34.9 kg/m(2)), 5.5%; and extremely obese (35-64.9 kg/m(2)), 11.5%. Percentages of GDM attributable to overweight, obesity, and extreme obesity were 15.4% (95% confidence interval [CI] = 8.6, 22.2), 9.7% (95% CI = 5.2, 14.3), and 21.1% (CI = 15.2, 26.9), respectively. The overall population-attributable fraction was 46.2% (95% CI = 36.1, 56.3).

CONCLUSIONS:

If all overweight and obese women (BMI of 25 kg/m(2) or above) had a GDM risk equal to that of normal-weight women, nearly half of GDM cases could be prevented. Public health efforts to reduce prepregnancy BMI by promoting physical activity and healthy eating among women of reproductive age should be intensified.