Babies of obese mothers have higher risk of some birth defects

Compared to normal-weight women, overweight and obese women suffer more pregnancy complications and their babies have more medical problems at birth, according to a position paper of the Public Affairs Committee of the Teratology Society.

The position paper published online February 3, 2006 in Birth Defects Research Part A: Clinical and Molecular Teratology, and is available via Wiley InterScience.

Obesity afflicts men and women of all ages across the United States and it is on the rise. Among women aged 20 to 39, more than half are overweight and nearly a third are obese, according to the National Health and Nutrition Examination Survey.

Obese women face increased risk of infertility and problems during pregnancy, including hypertension, gestational diabetes and thromboembolic events and are more likely to need a cesarean section. One French study found that overweight women had higher prenatal medical costs, and spent more time in the hospital recovering from childbirth.

In addition, the babies of obese mothers are more likely to be admitted to neonatal intensive care units. They also have a higher incidence of neural tube defects. "The literature suggests that compared to normal weight women, women whose body mass index (BMI) is greater than or equal to 30 have approximately double the risk of having an affected child," according to the Public Affairs Committee. The increased risk cannot be explained by folic acid intake, or by maternal diabetes.

The relationship between obesity and other birth defects remains unclear, according to the paper, because limited data is available, though some studies suggest a correlation.

"The Public Affairs Committee views obesity as a pregnancy risk factor and supports the public health initiatives identified by the FDA and the research initiatives identified by the NIH," the Committee writes. The national agencies are addressing the problem of obesity and acknowledging pregnancy as an important subject of further study.

The paper suggests that weight reduction efforts should be made well before conception is attempted, and dieters should avoid pregnancy. "Adequate nutrition is important for pregnant women and women planning pregnancy," the paper says. The committee recommends that clinicians counsel pregnant women about appropriate caloric intake and exercise.

While weight reduction surgery can improve the health and also the fertility of overweight women, the committee does not make a recommendation regarding surgery. They note that some recent reports have shown that women with gastric banding can have normal pregnancies and better pregnancy outcomes than obese women who do not have the surgery.

"Because some weight loss procedures can result in nutritional deficiencies, it appears reasonable to recommend that pregnancy be delayed until surgery-related weight loss has stabilized," writes the Committee.