my personal edition > paediatrics > news


  E-Mail this DGReview to a colleague

DGReview

Newborns of Obese Women at Increased Risk of Birth Defects

Women who are obese during pregnancy may have an increased risk of bearing children with certain types of birth defects, including spina bifida, omphalocele, and heart defects, according to an analysis by the United States Centers for Disease Control and Prevention (CDC).

According to the researchers, several studies have shown that pre-pregnancy maternal obesity is associated with an increased risk for neural tube defects, but few studies have examined the relation between maternal pre-pregnancy weight and other birth defects.

Margaret L. Watkins, BSN, MPH, and colleagues with the National Center on Birth Defects and Developmental Disabilities, CDC, Atlanta, Georgia, United States, conducted a population-based case-control study using data from the Atlanta Birth Defects Risk Factor Surveillance Study.

Mothers who delivered an infant with and without selected birth defects in a 5-county metropolitan Atlanta area between January 1993 and August 1997 were interviewed. The analysis involved 645 women who gave birth to children with a defect (cases) and 330 who did not (controls).

Maternal body mass index (BMI) was calculated and women were classified as obese women (BMI > 30), overweight (BMI 25.0 to 29.9), average weight (BMI 18.5-24.9), or underweight (BMI < 18.5).

The researchers found that obese women were 3.5 times more likely than average-weight women to have an infant with spina bifida (95% confidence interval [CI]: 1.2-10.3). Infants of obese women were also more likely to have omphalocele (odds ratio [OR]: 3.3; 95% CI: 1.0-10.3), heart defects (OR: 2.0; 95% CI: 1.2-3.4), and multiple anomalies (OR: 2.0; 95% CI: 1.0-3.8).

They also found that overweight women were more likely than average-weight women to have infants with heart defects (OR: 2.0; 95% CI: 1.2-3.1) and multiple anomalies (OR: 1.9; 95% CI: 1.1-3.4).

According to the researchers, the mechanism for the observed association between obesity and birth defects is unknown, but several possible explanations exist. For example, obese women may have diabetes or metabolic alterations, such as hyperglycaemia or elevated insulin or oestrogen levels. They might also consume a poor-quality diet or they may have an increased requirement for certain nutrients (eg, folic acid) known to be protective against birth defects.

"Although the biological mechanism(s) behind obesity and birth defects is unknown, efforts to ensure that reproductive-aged women are of healthy weight before pregnancy should not await the elucidation of the mechanisms," they conclude.

They also point out that the wide confidence intervals seen in this study "limit the conclusions possible."
Pediatrics 2003;111:5:1152-1158. "Maternal obesity and risk for birth defects"

E-Mail this DGReview to a colleague

To print, use this version