Obese pregnant women can safely diet: study

Obese pregnant women can safely limit their weight gain by watching what they eat, an analysis of several clinical trials suggests.

The study, reported in the journal Obstetrics & Gynecology, adds to evidence that obese women can try to limit their weight gain during pregnancy without harming themselves or their baby.

General recommendations from the Institute of Medicine (IOM), an advisory panel to the U.S. government, say that obese women should gain 11 to 20 pounds during pregnancy.

That's less than the 15 to 25 pounds recommended for overweight women, and the 25 to 35 pounds recommended for normal-weight women.

But some experts argue the IOM guidelines do not go far enough. They say at least some obese women can gain less weight - or even shed pounds - during pregnancy, to benefit their own health and to cut the risk of certain pregnancy complications.

The reality is that many obese women gain more than the IOM recommends.

So, small clinical trials have begun looking into ways to help obese women limit those pregnancy pounds.

For the new study, researchers combined the results of four of those trials - all looking specifically at diet counseling. They found that, on average, obese pregnant women who got diet help gained 14 pounds less than those who received no special advice.

They also saw no evidence that diet advice and weight loss harmed the infants' birth weights.

In addition, the lesser weight gain brought the women in line with IOM recommendations, say the researchers, led by Julie A. Quinlivan of Ramsay Health Care in Joondalup, Australia.

Dr. Raul Artal, head of obstetrics, gynecology and women's health at Saint Louis University School of Medicine, is one of the critics of the IOM guidelines for obese women.

"I think they are very generous," Artal told Reuters Health.

In his own research, Artal has found that obese women can safely maintain their weight, or even lose up to 10 pounds, without harming their newborn's birth weight - which has been the main concern with limiting pregnancy pounds.

Obese women are at increased risk of a number of pregnancy complications, including pregnancy-related diabetes, high blood pressure and having a larger-than-normal newborn - which can often necessitate a cesarean section.

Artal's research has suggested that when obese women maintain or lose a bit of weight during pregnancy, it not only does not seem to impair fetal growth, but may also curb the risk of having a larger-than-normal newborn.

That does not mean, however, that obese pregnant women should hop onto to the latest fad diet.

The four clinical trials in the current study included a total of 537 women who were randomly assigned to either a supervised dietary intervention or a "control" group. Women in the interventions received counseling on healthy eating and kept food "diaries" or other records to keep track of calories.