ORIGINAL RESEARCH
Racial/Ethnic Differences in the Percentage of Gestational Diabetes Mellitus Cases Attributable to Overweight and Obesity, Florida, 2004-2007
| Body Mass Index Category | Total | Non-Hispanic White | Non-Hispanic Black | Asian/Pacific Islander | American Indian | Hispanic |
|---|---|---|---|---|---|---|
| % | ||||||
| Underweight | 2.3 | 2.7 | 1.1 | 5.7 | 1.3 | 1.4 |
| Normal weight | 31.4 | 32.7 | 19.4 | 59.8 | 19.0 | 31.8 |
| Overweight | 26.9 | 25.2 | 28.5 | 23.1 | 24.1 | 30.0 |
| Class I obese | 19.6 | 19.1 | 23.5 | 8.6 | 22.8 | 20.1 |
| Class II obese | 11.1 | 11.4 | 14.4 | 1.9 | 15.2 | 10.0 |
| Class III obese | 8.7 | 8.9 | 13.1 | 0.8 | 17.7 | 6.7 |
Figure 1. Percentage of deliveries among women with gestational diabetes mellitus in each body mass index (BMI) category, total and by race/ethnicity, Florida, 2004-2007. BMI (kg/m2) categories for all races/ethnicities defined by the National Heart, Lung, and Blood Institute (15) as follows: underweight, <18.5; normal weight, 18.5-24.9; overweight, 25.0-29.9; obese, ≥30.0.
We used logistic regression with locally weighted smoothing (LOESS) to estimate the probability of GDM as a continuous function of prepregnancy BMI. This allowed us to evaluate the dose-response relationship between maternal BMI and GDM prevalence for each racial/ethnic group. The probability of GDM increased with increasing BMI for all racial/ethnic groups. The curve for All Races combined is somewhat nonlinear, with the slope diminishing slightly with increasing BMI. The angle of this curve is approximately 25 degrees from the horizontal. Only the curve for the non-Hispanic black group falls below the All Races curve; all other curves are above the All Races curve. All curves except that for the Asian/Pacific Islander group are very close to each other for BMI <25 kg/m2. The Asian/Pacific Islander curve is very notably above the other curves even at low BMI, and is considerably steeper than any of the other curves. There was no clear BMI threshold below which a dose-response relationship was not evident, although GDM risk increased only slightly with increasing BMI for BMI<20 kg/m2.
Figure 2. Smoothed estimated probability of gestational diabetes mellitus (GDM), by prepregnancy body mass index (BMI) and race/ethnicity, Florida, 2004-2007. BMI categories (kg/m2) defined by the National Heart, Lung, and Blood Institute (15) as follows: underweight, <18.5; normal weight, 18.5-24.9; overweight, 25.0-29.9; class I obese, 30.0-34.9; class II obese, 35.0-39.9; and class III obese, ≥40.0.
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