Study finds pre-pregnancy obesity poses increased risk of heart defects in babies

ATLANTA The largest study of obesity during pregnancy and babies with heart defects in the United States found that women who were overweight or obese before they became pregnant had an approximately 18% increased risk of having a baby with certain heart defects, compared with women who were of normal body mass index before they became pregnant, the Centers for Disease Control and Prevention announced in a press release issued Thursday.

Severely obese women had approximately a 30% increased risk, according to the CDC study, “Association Between Prepregnancy Body Mass Index and Congenital Heart Defects,” recently published in the American Journal of Obstetrics and Gynecology.

 “Congenital heart defects are the most common types of birth defect, and among all birth defects, they are a leading cause of illness, death, and medical expenditures,” stated Edwin Trevathan, director of the CDC?s National Center on Birth Defects and Developmental Disabilities. “Women who are obese and who are planning a pregnancy could benefit by working with their physicians to achieve a healthy weight before pregnancy.”

The study looked at 25 types of heart defects and found associations with obesity for 10 of them. Five of these 10 types were also associated with being overweight before pregnancy. Women who were overweight but not obese had approximately a 15% increased risk of delivering a baby with certain heart defects.

“These results support previous studies, as well as provide additional evidence, that there is an association between a woman being overweight or obese before pregnancy and certain types of heart defects,” added Suzanne Gilboa, epidemiologist at CDC?s National Center on Birth Defects and Developmental Disabilities, and primary author of the study. “This provides another reason for women to maintain a healthy weight. In addition to the impact on a woman?s own health and the known pregnancy complications associated with maternal obesity, the baby?s health could be at risk.”

One important limitation of the study is that BMI was calculated based on self–reported weight and height, and weight may have been underreported by women during the study interview. Although the study found an association between overweight and obesity and the risk of certain birth defects, further study is needed to determine whether body weight is the direct cause of these birth defects, the agency noted.

The analysis included 6,440 infants with congenital heart defects and 5,673 infants without birth defects whose mothers were interviewed as part of the National Birth Defects Prevention Study. The NBDPS is funded by the CDC to collect information from mothers of children with and without birth defects in Arkansas, California, Georgia, Iowa, Massachusetts, New York, North Carolina, Texas and Utah. This study is the largest effort ever undertaken in the United States to identify risk factors for birth defects.

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