You may have read the headlines last week that The Institute of Medicine (IOM) is changing its guidelines for obese pregnant women. Instead of recommending that women who are obese gain at least 15 pounds during pregnancy, the IOM now recommends a weight gain of 11 to 20 pounds.

It’s a start. But, as the lead researcher of a new study of obese women, pregnancy and weight gain, I’m concerned that obese women are being told to gain any weight.

My study, which is being published today in the Journal of the National Medical Association, found that obese pregnant women who followed a well-balanced diet and gained little or no weight had maternal-fetal outcomes that were equal to or better than those who gained substantial weight.

As a specialist in high-risk pregnancies who has delivered more than 5,500 babies over a 35-year career and supervised the delivery of 12,000 more, I wasn’t surprised by the findings of our study. I know that those extra pounds mean extra risks for both mother and baby. Obesity greatly increases the chance of developing complications in pregnancy such as preeclampsia, stillbirth, and blood clots, among others.

Twenty-three of the more than 200 obese women in our study lost weight. The average weight gained was just 11 pounds. And yet, these women and their babies were at least as healthy as those who put on substantial pounds. There were fewer babies weighing 10 pounds or more, fewer cesareans, and the mothers were less likely to develop gestational diabetes.

You can read more about the study, here.

So, if you’re carrying significant extra weight, forget the old adage about eating for two. Believe it or not, for a pregnant woman of normal weight, only an additional 300 calories per day is needed during her pregnancy – the equivalent to a quart of skimmed milk per day.

– Yvonne S. Thornton, MD, MPH