Obese moms-to-be should gain less weight than currently recommended

Oct 2 2007

Severely obese women should lose weight during pregnancy, while obese women who are pregnant should gain less weight than currently recommended, a Saint Louis University study finds.

The research is the largest population-based study to look at the effect of weight gain during pregnancy by obese expectant mothers, says Raul Artal, M.D., study author and chairman of the department of obstetrics, gynecology and women's health at Saint Louis University School of Medicine.

“This study confirms what we've suspected all along -- that obese women don't have to gain any weight during their pregnancy,” Dr. Artal says.

The study, published in the October issue of Obstetrics & Gynecology, analyzed the pregnancies of more than 120,000 obese women from Missouri to see how weight gain affected preeclampsia, which is high blood pressure brought on by pregnancy; cesarean delivery; and birth size.

Limiting weight gain of obese women during pregnancy has many benefits, the study shows. Women who have a BMI of 35 and gain fewer than the currently recommended 15 pounds are less likely to develop preeclampsia, less likely to need a cesarean delivery and more likely to have a baby of normal weight. A BMI of 18.5 to 24.9 is considered normal weight.

“Obese and overweight women should gain very little weight at all,” Dr. Artal says.

The findings run counter to current recommendations developed by the Institute of Medicine in 1990 that suggest women should gain at least 15 pounds during pregnancy and places no upper limit on pregnancy weight gain.

“Guidelines for nutrition during pregnancy at that time were based solely on expert opinion and not on scientific data. Obesity was not the problem it is now,” Dr. Artal says.

The study found that women of different weights should gain or even lose different amounts of weight.

The findings are significant in addressing a major public health crisis, Dr. Artal says.

“Fifty percent of Missouri's population is either overweight or obese. The problem is also prevalent in many other states in the country. Pregnancy is a big factor in this epidemic,” he says.

“It's been shown in the literature time and time again. Weight gain increases in subsequent pregnancies because women accumulate weight with each pregnancy and don't lose it.”

What mom does often determines the behavior of the rest of the family, Dr. Artal adds. “This is a multi-generational problem. The behavior modification starts with mom. If mothers are overeating and not exercising, that's how the rest of the family is likely to behave.”