Women's Health: Weight loss during pregnancy is OK for obese women

Gaining weight during pregnancy is normally considered essential for a healthy baby, but new research indicates it is safe for obese women to gain no weight, and even shed pounds, while pregnant.

"There was always a concern that women should not lose any weight in pregnancy because this may affect their fetuses," says Dr. Raul Artal, lead study author and chairman of obstetrics, gynecology and women's health at Saint Louis University in St. Louis, Missouri. "For too long we've prescribed obese pregnant women very generous diets, and that resulted in complications on the maternal side and also on the fetal side."

Complications can include high blood pressure, gestational diabetes (a form of high blood sugar that occurs during pregnancy) and the need for surgery to deliver the baby. There's also the danger that obese women will keep their extra weight long after the pregnancy.

Artal and his colleagues studied 96 overweight or obese pregnant women who had developed gestational diabetes and had enrolled in a diet and exercise program or a diet-only program.

The women in the exercise group gained significantly less weight during pregnancy than those in the diet alone group -- an average increase of 0.1 kilograms per week compared with 0.3 kilograms per week.

Thirty women maintained their weight or lost weight during pregnancy, and 66 women gained weight. Those who gained weight were more likely to give birth to an abnormally large baby. There were 10 of these infants in the weight-gain group, but only one in the no-gain group.

"A restrictive diet combined with some form of physical activity is beneficial to both mom and baby," Artal says.

The diets in the study were based on the women's weight and consisted of 25 calories per kilogram of body weight for overweight women, 20 calories per kilogram for obese women and 15 calories per kilogram for severely obese women.