Obesity During Pregnancy: Can It Harm Baby?

Feb. 3, 2006 — -- Being obese during pregnancy has a negative effect on women and their babies and can lead to an increased risk of birth defects, according to a committee of fetal development scientists and physicians.

Common complications to the baby include various types of birth defects, macrosomia (large body size), and shoulder dystocia, a potential life-threatening complication during labor in which the baby's shoulder cannot pass easily through the birth canal, the committee said in statement published in the journal, Birth Defects Research.

Most importantly, the risk of fetal neural tube defects, such as spina bifida, is doubled in obese women when compared to normal weight women. However, this risk is not due to maternal diabetes or a low folic acid intake -- two factors that have been shown to increase the risk of neural tube defects, researchers said.

Instead, one explanation for the increased risk of spina bifida could be that it is more difficult to detect neural tube defects with ultrasounds in obese women because of the lower quality of images, said Dr. Jacques Moritz, director of gynecology at St. Luke's-Roosevelt Hospital in New York.

"In most women where the defect is detected early on, the pregnancy is electively terminated," Moritz said.

The committee decided to analyze weight's effect on maternal and fetal health after a increasing amount of reports pointed to obesity negatively impacting health, said Dr. Anthony Scialli of Sciences International, Inc., and an author of the paper.

The hope is to, "bring [this issue] to the attention of the public and practitioners," he said.

Complications to the obese mother include pregnancy-related high blood pressure and diabetes, and a higher risk of forming dangerous blood clots. Obese mothers also are more likely to undergo caesarean section surgery, have post-operative infections, and spend more time recovering in the hospital after childbirth, the report stated.

Losing weight by dieting and exercise is important since even modest weight loss can make a difference, the statement said. A caveat, however, is that weight reduction efforts should be made well before conception is attempted.

The committee cautioned women that dieting just before or during pregnancy can be dangerous since adequate nutrition and appropriate caloric intake is necessary for both pregnant women and the growing fetus.

For particularly heavy patients, another option may be weight-reduction surgery, said Dr. Mitchell Roslin, director of Obesity Surgery at Lenox Hill Hospital.

Not only is it good for their health, losing weight also will help patients conceive by increasing their fertility because the ratio of their sex hormones will change, Roslin said.

Dr. Sandra Carson, an obstetrics and gynecology professor at Baylor College of Medicine, also recommends weight-loss surgery for morbidly obese.

"After surgery, I recommend they wait 18 months before trying to conceive…this way the rapid weight loss stabilizes," Carson said.

Although the committee said in their paper that they can't yet recommend weight loss surgery for all obese women, they noted studies suggesting that the surgery has benefits for both mom and baby.

Notably, women who underwent stomach bypass surgery had health risks comparable to normal weight women during pregnancy, and their babies were similar to those born to normal-weight women.

The committee also stressed the importance of educating parents about appropriate childhood nutrition to establish good lifelong eating habits and proper weight management.

"Breast-feeding should be encouraged based on evidence of a protective effect against childhood obesity, as well as other health advantages," the paper said.

Ultimately, the statement said the decision regarding weight management should be discussed individually between a woman and her doctor.

Dr. Rajesh V. Swaminathan is a medical resident at Massachusetts General Hospital.