Heart Defects, Mom's Weight May Be Linked
Being Overweight or Obese Before Pregnancy May Be Tied to Increased Risk of Congenital Heart Defects
Oct. 1, 2009 -- Women who are overweight or obese before getting pregnant
may be more likely than leaner women to have babies born with heart defects, a
new study shows.
The study, published in the advance online edition of the American
Journal of Obstetrics and Gynecology, included the mothers of 6,440 babies
born with congenital heart defects between 1997 and 2004.
In telephone interviews, the mothers reported their pre-pregnancy height,
weight, and various lifestyle and medical factors.
For comparison, the researchers asked the same questions of 5,673 women who
had babies during the same time period without heart defects.
Compared to women with a normal BMI (body
mass index), women who were overweight but not obese before pregnancy were
16% more likely to have a baby born with a heart defect.
By the same comparison, women who were moderately obese before pregnancy
(BMI of 30-34.9) were 15% more likely to have a baby born with heart
Women who were severely obese before pregnancy (BMI greater than 35) were
31% more likely to have a baby born with a heart defect.
"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, MD, MPH, director of the CDC's National
Center on Birth Defects and Disabilities, says in a news release.
"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 doesn't prove that the women's extra weight caused birth defects
in their babies. Observational studies like this one can show associations, but
they don't prove cause and effect.
Also, the women reported their height
and weight; they weren't measured. Self reports of weight aren't always
accurate, and that could have affected the results.
However, the researchers considered factors including maternal age, and they
excluded mothers with type 1 or type 2 diabetes, because
diabetes is a strong risk factor for 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," Suzanne Gilboa,
PhD, an epidemiologist at CDC's National Center on Birth Defects and
Developmental Disabilities, says in a news release.
"This provides another reason for women to maintain a healthy weight. In
addition to the impact on a woman's own health and known pregnancy
complications associated with maternal obesity, the baby's
health could be at risk," says Gilboa, who worked on the new study.
Gilboa's study only compares the odds of having a baby with a heart
defect; it doesn't show the odds that any given woman, of any size, would have
a baby with a heart defect.