IOM Updates Guidelines for Weight Gain in Pregnancy

The Institute of Medicine's guidelines for weight gain during pregnancy have been updated for the first time in nearly 20 years. Although the new guidelines (4-page PDF; About PDFs) don't differ drastically from the previous ones, members of the committee that drafted the document say they hope physicians and women will pay closer attention to this version.

Committee member Patrick Catalano, M.D., obstetrics chairman at of the OB/Gyn department at Case Western Reserve University, Cleveland, said physicians need to counsel women about their weight before conception, during pregnancy and postpartum.

"Some health care providers might not be going into as much detail as we would like," Catalano said during a May 28 news conference announcing the release of the guidelines. "When you individualize efforts, your results might be better. All women should be made aware of this."

According to committee member Anna Maria Siega-Riz, Ph.D., R.D., L.D.N., of the department of epidemiology at the University of North Carolina at Chapel Hill's School of Public Health, most pregnant women aren't given an appropriate weight range to strive for by their physicians.

The new guidelines differ from the 1990 guidelines in a few areas. First, the ranges for weight gain are based on body mass index, or BMI, measures, rather than on the Metropolitan Life Insurance tables used previously.

The new guidelines also include a specific, narrow range of recommended weight gain for obese women. Obese women previously were advised to gain at least 15 pounds with no maximum limit. The new guidelines call for a total range of 11-20 pounds for obese women expecting a single infant.

The study says that 8 percent of U.S. women of reproductive age are severely obese (i.e., BMI >30.0), compared with just 3 percent who are underweight (i.e., BMI <18.5).

Suggested ranges of weight gain for other groups are 28-40 pounds for underweight women, 25-35 pounds for normal-weight women (i.e., BMI 18.5-24.9) and 15-25 pounds for women who are overweight (i.e., BMI 25.0-29.9).

Unlike the 1990 recommendations, the new guidelines say there is no evidence for further modifying the weight-gain ranges for women who are short, members of a minority group or teenagers.

Separate guidance applies to women pregnant with twins. Those with a normal BMI should gain 37-54 pounds, overweight women should gain 31-50 pounds, and obese women should gain 25-42 pounds.

The committee acknowledged that although "the guidelines developed as part of this committee process are not dramatically different from those published previously, fully implementing them would represent a radical change in the care provided to women of childbearing age."

Specifically, the committee said, full implementation of the guidelines would necessitate "offering preconceptional services, such as counseling on diet and physical activity, as well as access to contraception, to all overweight or obese women to help them reach a healthy weight before conceiving." Taking these steps, the authors noted, could result in reduced obstetric risk, normal infant birth weights and improved long-term maternal health.

In addition, counseling all pregnant women on diet and exercise could be expected to provide those benefits, as well as reduce postpartum weight retention and reduce childhood obesity, the report said. And pospartum counseling could help women conceive subsequent children at a healthy weight and improve long-term health.

Catalano said pregnant women who do not have pre-existing conditions should be encouraged to engage in generalized exercise, such as walking or swimming.

Coincidentally, a study on weight gain in pregnant women that was published in the May issue of the American Journal of Obstetrics and Gynecology showed that consuming 500 extra calories a day increased a woman's odds of gaining too much weight by 10 percent.

Alison Stuebe, M.D., assistant professor of OB/Gyn at the University of North Carolina at Chapel Hill, and her co-authors found in the study of more than 1,000 pregnant women that consumption of extra calories, dairy products and fried foods were associated with gaining too much weight, which can lead to complications such as pre-eclampsia.

The study also reported that women who exercised 30 minutes a day reduced their risk of gaining excess weight by 20 percent.