Pregnancy weight gain due for review
■ Experts say the old targets need to be revised to take into account the obesity epidemic and the long-term health of women and children.
By Victoria Stagg Elliott — Posted Sept. 10, 2007
"Eating for two" may soon not be much of an excuse.
New guidance on how much weight to gain while pregnant has not been issued by the Institute of Medicine since 1990, but the agency is expected to initiate the revision process within the next few months. "This is a topic of great interest," said Christine Stencel, IOM spokeswoman.
The agency hosted a workshop in May 2006 regarding the impact of pregnancy weight on maternal and child health. The objective was to consider this issue without making new recommendations, but experts now say revised guidance that encourages healthier eating and physical activity during this time is desperately needed.
Evidence has begun to indicate that women may be gaining too much, even if they stay within the accepted boundaries. The emphasis on prenatal health is also shifting to encompass a woman's and child's welfare not just during and immediately after pregnancy and birth but also far in the future.
"It's long overdue," said Raul Artal, MD, professor and chair of the department of obstetrics, gynecology and women's health at Saint Louis University in Missouri. "I would like the panel to put together new guidelines that recognize that pregnancy is not a state of confinement and women should not eat for two."
Current recommendations, more than a decade old, call for underweight women to gain between 28 lbs. and 40 lbs. Those with a normal body mass index should gain 25 lbs. to 35 lbs. Overweight women are encouraged to add 15 lbs. to 25 lbs. and those who are obese at least 15. These ranges represented an increase from previous guidelines and were issued in response to concerns about low-birthweight, pre-term birth and an increased risk of neurologic defects.
With the obesity epidemic having since taken hold, physicians say inadequate weight gain is no longer an issue. Many women gain far more, which has also been implicated in an increased risk of complications in the newborn. These women also have problems losing the weight after the birth, putting themselves at an increased lifetime risk for being overweight or obese. Additionally, many experts believe the circumstance of low-birthweight babies is not caused by their mothers' undereating.
"Many women are now coming into pregnancy with weights that are too high and are apparently gaining excessive amounts during pregnancy," said Matthew W. Gillman, MD, a member of the planning group for the previous workshop and director of the obesity prevention program at Harvard Pilgrim Health Care in Boston.
Some evidence also notes that the recommended weight gain may not be healthy over the long term. For instance, a study published in the April American Journal of Obstetrics and Gynecology found women who gained more than or in accordance with the guidelines were four times more likely to have a baby who was overweight at age 3 than were women who did not gain enough. These children also had higher systolic blood pressures.
"We have started to recognize the longer-term implications beyond just pregnancy. The evidence is pointing in the direction that gaining too much weight is unhealthy and that women should be gaining less," said Emily Oken, MD, MPH, lead author on that paper and assistant professor of ambulatory care and prevention at Harvard Medical School in Boston.
Some data also suggest that women carrying the most excess weight may not need to gain much, if any, to have the healthiest baby possible and that shedding pounds while pregnant may even be beneficial. Another study by Dr. Artal in the June Applied Physiology, Nutrition and Metabolism found that obese women with gestational diabetes who did not gain or who lost some weight using a diet alone or in combination with exercise, gave birth to babies who were just as healthy as those of mothers who added pounds.
"There's a lot of controversy whether obese women really even need to gain any weight or if losing weight is safe or not," said Naomi Stotland, MD, assistant professor of obstetrics and gynecology at the University of California, San Francisco.
This question is particularly relevant during pregnancy. Many experts view these months as a time when women are the most amenable to recommendations for healthy lifestyle changes because of concerns about the baby.