Maternal Obesity, Overweight Linked to Congenital Heart Defects

From Medscape Medical News
Laurie Barclay, MD

October 2, 2009 — Maternal obesity and overweight before pregnancy are linked to congenital heart defects (CHDs) in the offspring, according to the results of a large case-control study reported in the October issue of the American Journal of Obstetrics & 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," Dr. Edwin Trevathan, director of the US Centers for Disease Control and Prevention's (CDC) National Center on Birth Defects and Developmental Disabilities, said 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 goal of this analysis from the National Birth Defects Prevention Study (NBDPS) was to evaluate associations between prepregnancy body mass index (BMI) and CHDs in the offspring. Case infants with CHDs (n = 6440) were compared vs 5673 liveborn control infants without birth defects enrolled in the NBDPS from 1997 to 2004.

For all CHDs combined, adjusted odds ratios were 1.16 for overweight status (95% confidence interval [CI], 1.05 - 1.29), 1.15 for moderate obesity (95% CI, 1.00 -1.32), and 1.31 for severe obesity (95% CI, 1.11 - 1.56). Phenotypes of CHD associated with maternal BMI of at least 25.0 kg/m2 were conotruncal defects (tetralogy of Fallot), total anomalous pulmonary venous return, hypoplastic left heart syndrome, right ventricular outflow tract (RVOT) defects (pulmonary valve stenosis), and septal defects (secundum atrial septal defect).

The study authors concluded that these findings supported those from previous research and also highlighted new associations between obesity and conotruncal defects and RVOT 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," said lead author Suzanne M. Gilboa, PhD, epidemiologist at CDC's National Center on Birth Defects and Developmental Disabilities. "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."

Limitations of this study include BMI calculated from self-reported weight and height, some missing data for prepregnancy BMI, 70% response rate in the NBDPS, and inability to determine any causal relationship between maternal body weight and CHDs. In addition, study centers in Massachusetts and New Jersey did not ascertain case infants among pregnancy terminations, and New York began ascertaining pregnancy terminations only in the year 2000.

The NBDPS is funded by the CDC. The views expressed in the journal article are those of the study authors and do not necessarily represent the official position of the CDC.

Am J Obstet Gynecol. Published online October 1, 2009.