Weight Gain during Pregnancy - latest guidelines

Institute of Medicine Sets New Guidelines for Weight Gain During Pregnancy
Fran Lowry
From Medscape Medical News

May 28, 2009 — The Institute of Medicine and the National Research Council today released a report recommending new guidelines for weight gain during pregnancy. The report updates guidelines that were last set in 1990 and takes into account changing US demographics, particularly the increase in the numbers of women of childbearing age who are overweight and obese.

The new guidelines are available on the Institute of Medicine's Web site.

"The earlier guidelines recommended weight gain that would be optimal for the baby. These new guidelines take into account the well-being of the mother as well. This is a fundamental and important change," Kathleen M. Rasmussen, ScD, professor of nutrition at Cornell University and chair of the guidelines committee, said at a press briefing where the new recommendations were announced.

The 2009 guidelines also differ from those issued 2 decades ago in 2 other ways. They are based on World Health Organization cutoff points for body mass index (BMI) categories, unlike the earlier guidelines, which were based on weight categories taken from the Metropolitan Life Insurance tables. They also recommend a more narrow range of weight gain for obese women.

The recommended weight gain for each category of prepregnancy BMI is as follows:

• Underweight (< 18.5 kg/m2); total weight gain range: 28 to 40 pounds

• Normal weight (18.5 - 24.9 kg/m2); total weight gain range: 25 to 35 pounds

• Overweight (25.0 - 29.9 kg/m2); total weight gain range: 15 to 25 pounds

• Obese (≥ 30.0 kg/m2); total weight gain range: 11 to 20 pounds

"Women who gain within these guidelines will do better than if they gain outside of them. We have good evidence for this," said Dr. Rasmussen.

Currently in the United States, 55% of women between the ages of 20 and 39 years are overweight, and approximately one half of these are obese, with a BMI higher than 25 kg/m2. Eight percent of obese women are severely obese, with a BMI of 40 kg/m2 or greater, Dr. Rasmussen said.

She conceded that getting obese women to restrict their gestational weight gain to no more than 20 pounds would be a challenge. Still, she insisted, it is doable. She told Medscape Ob/Gyn & Women's Health: "The studies that we reviewed showed that many obese women gain progressively less weight the heavier they are. We also think that if these women are counseled about the importance of restricting their weight gain, they can be successful.

For example, in a study from Denmark, obese women who were given individualized care and attention were able to restrict their weight gain during pregnancy and achieved better outcomes. We realize that it will be difficult and expensive to achieve this, but we think it is worth trying to replicate such experience here."

The new guidelines stress the importance of preconception counseling to ensure women of childbearing age are at a healthy weight before they become pregnant. However, Dr. Rasmussen admitted to Medscape Ob/Gyn & Women's Health that the committee did not yet have any data on the success of such counseling.

"These data provide a strong reason to assume that interventions will be needed to assist women, particularly those who are overweight or obese at the time of conception, in meeting the guidelines. These interventions may need to occur at both the individual and community levels and may need to include components related to both improved dietary intake and increased physical activity," she told reporters at the press briefing.

The guidelines also recommended that research on dietary intake, physical activity, dieting practices, food insecurity, and how the social and environmental context affect gestational weight gain be supported financially.

Although the new guidelines may be applicable to women in other developed countries, they are not intended for use in areas of the world where women are substantially shorter or thinner than women in the United States or where adequate obstetric services are unavailable, Dr. Rasmussen added.

IOM (Institute of Medicine). Weight Gain During Pregnancy: Reexamining the Guidelines. Washington, DC: The National Academies Press. Posted online May 28, 2009.