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Leading Ob-Gyn Group Backs Findings of My Weight Gain in Pregnancy Study

Tuesday, January 12th, 2010

Last June, in the Journal of the National Medical Association, I published the results of clinical trials that showed that it was safe for obese pregnant women who followed a well-balanced diet to gain little or no weight. Prior to my study, the conventional wisdom was that all women, even obese ones, should gain 26 to 35 pounds. That guidance had come from the most august body of ob-gyns in the U.S., The American College of Obstetricians and Gynecologists (ACOG), whose recommendations were based upon what we knew in the 1980s. That was before we fully understood the dangers of obesity in pregnancy. Yet, the guidelines had never been updated.

Being obese during pregnancy greatly increases the risks of preeclampsia, diabetes, stillbirth, and blood clots, among other problems. Gaining more weight if you’re already obese makes complications more likely while limiting weight gain makes them less so.

But until my study was published, obstetricians lacked the evidence that limiting weight gain among pregnant women was safe. The ACOG’s guidance from the 1980s stated that, unless a woman, obese or not, gained at least 26 pounds, the baby in her womb would be at risk of dying.

Right before my study results were published, a government body recommended that obese women gain somewhat less weight: between 11 and 20 pounds. It was a start but still not enough. And most board certified obstetricians would wait for the ACOG to – you’ll excuse the pun – weigh in before they changed their practices.

I’m delighted to say that, in a commentary in the peer-reviewed journal Obstetrics & Gynecology, the ACOG has just come out in favor of limiting weight gain among obese pregnant women. My study, which was quoted in the commentary, appears to have been instrumental in effecting this turnaround.

Now that the ACOG is changing its recommendations, obstetricians are more likely to change how they manage their patients. Fewer women will be told that it’s fine to gain weight during pregnancy if you’re already obese. And that will mean healthier moms and healthier babies.

I’m proud to have played a role in helping to make this happen.

– Yvonne S. Thornton, MD, MPH

More media attention for the study

Friday, June 5th, 2009

Forbes reports on my study, showing that obese pregnant women should limit weight gain as does Medline.

Other media outlets giving the study prominent coverage are United Press International, Yahoo News, The Baltimore Sun, US News and World Report, and even the Times of India.

– Yvonne S. Thornton

My study on obesity and pregnancy in the news

Wednesday, June 3rd, 2009

I’m pleased to see that the media is getting the word out: obese pregnant women should be eating healthier diets and limiting their weight gain.

In the past few days, I’ve been interviewed by a number of news organizations about the study. You can see some of the reports at the following links:


The Atlanta Journal-Constitution

Science Daily

The Los Angeles Times

and Health Day

– Yvonne S. Thornton, MD, MPH

Study’s author concerned that new guidelines for pregnant obese women don’t go far enough

Tuesday, June 2nd, 2009

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