The Institute of Medicine and the National Research Council 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 2009 guidelines differ from those issued 2 decades ago in 2 ways:

1. 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.
2. 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 (BMI < 18.5); total weight gain range: 28 to 40 pounds
• Normal weight (BMI 18.5 - 24.9); total weight gain range: 25 to 35 pounds
• Overweight (BMI 25.0 - 29.9 ); total weight gain range: 15 to 25 pounds
• Obese (BMI ≥ 30.0) ; total weight gain range: 11 to 20 pounds

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.

Getting obese women to restrict their gestational weight gain to no more than 20 pounds would be a challenge but it can be done. 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.

The new guidelines stress the importance of preconception counseling to ensure women of childbearing age are at a healthy weight before they become pregnant.

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.

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