Mom's Obesity Tied to Baby's Heart Defects

Oct. 2, 2009— -- Women who are overweight during pregnancy may be putting their unborn children at risk of congenital heart defects, new government research shows.

Compared with women of normal weight at the beginning of pregnancy, overweight mothers had an 18 percent increased risk of giving birth to a child with certain heart defects, while the most severely obese had a 30 percent increased risk, according to Dr. Sonja Rasmussen, of the CDC's National Center on Birth Defects and Developmental Disabilities.

She and colleagues reported their findings online in the American Journal of Obstetrics and Gynecology.

"Since obesity is a common condition among women of child-bearing age and is increasing in the U.S. in prevalence, it's important for us to understand the impact obesity has on the risk for [all] birth defects," Rasmussen said.

She added that the findings "provide just one more reason why women should maintain a healthy weight … not only because of the impact on their own health, but because of the impact on their baby's health."

Previous research has not been consistent on the relationship between obesity and congenital heart defects, the researchers said.

So they looked at data from the National Birth Defects Prevention Study involving 6,440 infants with congenital heart defects and 5,673 infants without birth defects. The infants' mothers were interviewed between 1997 and 2004.

In general, mothers of infants with heart defects reported significantly more smoking, gestational diabetes, and hypertension during pregnancy than mothers of healthy babies.

The researchers found that overall, a pre-pregnancy body mass index (BMI) that was above normal was associated with an increased risk for several congenital heart defects.

When comparing by different BMI categories, overweight women had a 16 percent increased risk of having children with heart defects -- particularly right ventricular outflow tract defects, pulmonary valve stenosis, septal defects, and secundum atrial septal defects.