How Much Weight Should You Gain During Pregnancy?

New guidelines don't call for a big change but urge women to really stick to the recommendations.

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Since 1990, women have been told to gain between 25 and 35 pounds during pregnancy if they're at a healthy weight to begin with, and now—after an exhaustive review of current research—the Institute of Medicine today issued long-awaited new guidelines telling us to gain...25 to 35 pounds. Overweight women are now advised to gain 11 to 20 pounds, whereas before they were told to gain 15 pounds (with no upper limit explicitly stated). Underweight women are still told to gain around 30 to 40 pounds.

What's new here? Even the IOM admits in its report that "the guidelines developed as part of this committee process are not dramatically different from those published previously." The emphasis, rather, is on "fully implementing them." Studies show that 40 percent to 73 percent of pregnant women are not following the current weight gain guidelines, says Kathleen M. Rasmussen, chair of the nutrition department at Cornell University and an editor of the new guidelines. What's more, doctors aren't educating women about what to eat and how to exercise during pregnancy.

For this reason, the report calls for preconception counseling for overweight women to improve their diets and increase their activity levels with the goal of having them lose weight before getting pregnant. That's a tall order. About half of women getting pregnant these days are overweight or obese, compared with just 30 percent in the 1970s. That puts them at increased risk of complications like gestational diabetes and pre-eclampsia. And a mother who gains an excess amount of weight during pregnancy, which overweight women are apt to do, increases her baby's risk of obesity in childhood.

I'm guessing that many experts will complain that the guidelines are a lot of nothing new. The Centers for Disease Control and Prevention already called for preconception care back in 2006, yet many women still aren't getting a full range of counseling from their primary-care physicians or gynecologists. And while the IOM panel of experts called for nutrition and exercise counseling by nutritionists or a fitness trainer, if necessary, they didn't address how women should go about getting that guidance if their insurance doesn't cover these services.

"We weren't asked to do this in our review," says IOM panel member and public health expert Anna Maria Siega-Riz at the University of North Carolina-Chapel Hill, in response to my question during a press conference this morning. "But we're hoping that once we make a call for action, public health experts, physicians, and women themselves and public health experts will be calling for these services."

Some doctors were hoping that the recommended weight guidelines would be shifted downward. Several recent studies have suggested that both women and babies benefit in terms of preventing future obesity when women gain closer to 25 pounds as opposed to 35 pounds. Gary Hankins, chair of the Obstetric Practice Committee of the American College of Obstetricians and Gynecologists, previously told me that he advises patients who begin their pregnancies at a healthy weight to gain less than the recommended amounts for this reason. "I tell women that 15 to 20 pounds is a really good target to shoot for and that they shouldn't gain more than 25 pounds," he says. Although he would recommend a larger weight gain if a baby were not growing properly, Hankins says that this amount is usually enough to ensure a healthy baby and makes it easier for women to get back to their prepregnancy weight.

But the IOM members say they had women in mind as well as the research. Realistically, it's far easier to shoot for 30 pounds than 20, and the science isn't compelling enough to go back to the 1970s recommendations for pregnant women to gain 20 to 25 pounds.

If you're already pregnant and have gained too much, don't panic. "Our message to pregnant women is not that if you've gained too much, you need to stop," says Siega-Riz, "but that you need to take stock of where you're at and start gaining correctly." The IOM has weekly weight gain guidelines, too: about 1 pound a week during the second and third trimesters if you have a healthy body mass index of 19 to 25 or are underweight (below 19), and about one-half pound per week if you're overweight (over 25).

[Here's how to calculate your body mass index.]