Risk of Adverse Pregnancy Outcomes Associated with Diabetes Varies by Women's Race and Ethnicity
Women with diabetes have an increased risk of adverse pregnancy outcomes, but the level of risk associated with the condition varies by racial and ethnic group, according to an analysis of births in New York City.1 Among white, black, Hispanic and Asian groups alike, women with chronic or gestational diabetes had higher odds than their nondiabetic counterparts of having a first cesarean delivery (odds ratios, 1.2–2.9) or a preterm birth (1.2–3.4). Chronic diabetes was positively associated with the likelihood of having a low-birth-weight infant among white, Hispanic and Asian women (1.6–2.3), and gestational diabetes was negatively associated with this outcome among black and Hispanic women (0.7–0.8).
Using data from birth certificates, researchers studied births during 1999–2001. They conducted logistic regression analyses to test associations between two maternal risk factors—obesity and diabetes—and three adverse pregnancy outcomes—a first cesarean delivery, preterm birth (delivery before 37 weeks of gestation) and birth of an infant with a low birth weight (less than 2,500 g). The regression models were adjusted for social and demographic factors potentially affecting pregnancy outcomes (maternal age, marital status, birthplace and education; parity; payer for prenatal care; trimester in which prenatal care began; smoking and use of alcohol and drugs; and, in parts of the analysis, preeclampsia).
Analyses were based on live singleton births to 329,988 women, of whom 33% were Hispanic, 29% were white, 26% were black and 12% were Asian. The women were 28 years old, on average. Six percent were overweight or obese (weighing 200 lbs. or more) before becoming pregnant, and 18% gained excess weight (41 lbs. or more) during pregnancy. Fewer than 1% had chronic (type 1 or type 2) diabetes, but 4% developed gestational diabetes. In addition, about 1% each had chronic hypertension and pregnancy-induced hypertension, and 2% developed preeclampsia. Overall, 15% of the women had a first cesarean delivery, 8% had a preterm birth and 6% had an infant with a low birth weight. In general, black women had the highest prevalence of risk factors and poor pregnancy outcomes; white and Asian women tended to have the lowest prevalence.
In the overall population, relative to women who had a normal weight (100–149 lbs.) before pregnancy, women who were overweight or obese had increased odds of having a first cesarean delivery (odds ratios, 1.9–2.6), reduced odds of giving birth to an infant with low birth weight (0.7–0.8) and similar odds of preterm birth. And compared with their counterparts who did not gain excess weight during pregnancy, women who did had an increased likelihood of a first cesarean delivery (1.4), but a reduced likelihood of preterm birth (0.5) and of delivering a low-birth-weight infant (0.4). Chronic diabetes was positively associated with the odds of first cesarean birth (2.4), preterm birth (2.5) and delivery of a low-birth-weight infant (1.6). Gestational diabetes was also positively associated with the odds of a first cesarean birth (1.5) and preterm birth (1.3), but was negatively associated with the odds of a having a low-birth-weight infant (0.9).
In each racial or ethnic group, women who had chronic diabetes had elevated odds of a first cesarean delivery relative to their nondiabetic counterparts; odds were least elevated among Asian women (odds ratio, 2.0) and most elevated among Hispanic women (2.9). Similarly, women in all four groups who had chronic diabetes were more likely to have a preterm birth than were their counterparts without diabetes; odds were increased least among black women (2.0) and most among Hispanic women (3.4). White, Hispanic and Asian women who had chronic diabetes were more likely than their nondiabetic racial and ethnic counterparts to give birth to an infant with low birth weight (1.6, 1.7 and 2.3, respectively).
Racial and ethnic variations in risks associated with gestational diabetes were less marked. In all four groups, women with gestational diabetes had increased odds of a first cesarean delivery (odds ratios, 1.2–1.6) and of preterm birth (1.2–1.3). Black women and Hispanic women who developed gestational diabetes were less likely to have a low-birth-weight infant than were their racial and ethnic counterparts who did not develop diabetes during pregnancy (0.8 and 0.7, respectively).
"Although careful monitoring of diabetes during pregnancy can improve pregnancy outcomes for diabetic women," the investigators contend, "the longer-term public health approach should be to prevent type 2 diabetes and gestational diabetes by controlling women’s weight over their lifetimes." They add that pregnancy and the postpartum period are a "window of opportunity" for counseling women about healthy behavioral changes. They suggest that "lifestyle changes in nutrition and exercise be promoted by all primary care providers, including obstetricians."
1. Rosenberg TJ et al., Maternal obesity and diabetes as risk factors for adverse pregnancy outcomes: differences among 4 racial/ethnic groups, American Journal of Public Health, 2005, 95(9):1545–1551.