Pregnancy Weight-Gain Debate

Should very heavy women put on fewer pounds than doctors now recommend?

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Nearly 30 percent of American women today are obese when they begin their pregnancies. This means they have a body mass index (BMI) of 30 or higher, as would a 5-foot-4-inch woman who weighs 175 pounds. Now, how much weight these women should gain while pregnant is being debated.

The federal government updated its pregnancy guidelines in 2009, concluding that gaining 11 to 20 pounds is ideal. But that’s too much, argues researcher Raul Artal, M.D., chairman of OB-GYN at Saint Louis University School of Medicine. For obese pregnant women, he recommends a nutritious diet of 2,000 to 2,500 calories a day, which would lead to a weight gain of no more than 10 pounds and, in some cases, even weight loss. Nearly 75 percent of obese women currently put on more than 15 pounds during pregnancy.

Studies linking excess pregnancy weight gain with health problems for moms and babies are mounting. The risks include gestational diabetes, hypertension, Cesarean sections, bigger babies and birth injuries, as well as the likelihood of retaining more weight postpartum. Larger babies are more likely to have metabolic abnormalities, certain birth defects and less-mature organs, and children of mothers who gain more than the recommended amount during pregnancy have a higher chance of being obese later in life. “Large moms deliver large girls, who in turn become obese and have large babies,” Artal says. “It’s a vicious cycle.”

Supporting a new look at the current recommendations, a 2007 study of 120,000 obese women found that those with a BMI of 35 or higher who gained fewer than 15 pounds or lost weight during pregnancy were less likely to have preeclampsia, a C-section or a large baby. Similar favorable outcomes were found in a 2009 study.

Waiting for more answers
The authors of the 2009 guidelines contend that there’s not yet enough high-quality data to recommend less weight gain for obese women. Experts are eagerly awaiting the 2012 results of an Australian study of weight-gain intervention among 2,500 overweight or obese pregnant women.

Unfortunately, most previous attempts to limit such women’s weight gain have failed. “It’s not all under your control,” says Naomi E. Stotland, M.D., an assistant professor of OB-GYN and reproductive sciences at the University of California, San Francisco, who has studied obesity in pregnancy. “The placenta secretes all kinds of hormones that, along with the genetic makeup of the fetus, may affect
appetite or metabolism,” she explains. “The most important things are eating healthfully and exercising, not what the scale says.”