FRIDAY, April 9, 2010 (HealthDay News) -- Obese pregnant women are at increased risk of having a baby with a congenital heart defect, a new study finds.
On average, obesity is associated with a 15 percent increased risk of having a baby with a heart defect. But the risk rises with the level of obesity. Compared to normal-weight women, the risk is 11 percent higher in moderately obese women and 33 percent higher in morbidly obese women.
In general, women who were overweight but not obese had no increased risk, said the researchers at the U.S. National Institute of Child Health and Human Development (NICHD) and the New York State Department of Health.
"The trend is unmistakable: the more obese a woman is, the more likely she is to have had a child with a heart defect," study first author Dr. James L. Mills, of the NICHD's Division of Epidemiology, Statistics and Prevention Research, said in a news release.
The study was published online April 7 in the American Journal of Clinical Nutrition.
"The current findings strongly suggest that by losing weight before they become pregnant, obese women may reduce the chances that their infants will be born with heart defects," Dr. Alan E. Guttmacher, acting director of the NICHD, said in the news release.
For this study, researchers compared the records of mothers of 7,392 children born with major heart defects and more than 56,000 mothers of infants born without birth defects. Because the study looked at the records of infants after they were born, it doesn't conclusively prove that obese women who lose weight before becoming pregnant will reduce their risk of having a baby with a heart defect, the researchers noted.
However, "if a woman is obese, it makes sense for her to try to lose weight before becoming pregnant," Mills said. "Not only will weight loss improve her own health and that of her infant, it is likely to have the added benefit of reducing the infant's risk for heart defects."
The March of Dimes has more about congenital heart defects.