Women who were overweight or obese before they became pregnant are significantly more likely to give birth to a baby with a heart defect, a study published Thursday showed.
The risk of having a baby with congenital heart defects was around 18 percent greater if a woman was overweight or obese when she became pregnant than it was among normal-weight women, the study conducted by the Centers for Disease Control and Prevention (CDC) found.
Researchers analyzed data on 6,440 infants with congenital heart defects and 5,673 infants without birth defects for the study, the results of which were published in the American Journal of Obstetrics and Gynecology.
Mothers with type 1 or 2 diabetes, which is a strong risk factor for heart defects, were excluded from the study.
Out of 25 types of heart defects that the researchers looked at, 10 were found to be associated with maternal obesity and five with the mother being overweight.
"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," Edwin Trevathan, director of the CDC's National Center on Birth Defects and Developmental Disabilities, said in a statement.
Two-thirds of American adults are either obese or overweight. The average American carries 23 superfluous pounds (11 kilos).
Obesity is defined as having a body mass index -- calculated by dividing a person's weight in kilograms by their height squared in meters -- greater than 30, while the official definition of overweight in women is having a body mass index greater than 27.3.
In health terms, being obese means a person is at greater risk for a whole host of maladies, ranging from high blood pressure to diabetes, heart disease and stroke -- and this study shows that the health risk can be passed on to children.
"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," said CDC epidemiologist Suzanne Gilboa.
According to a report issued in July, obesity could account for one in six dollars spent on health care by 2030.