Conference Coverage

Women with obesity need not boost calories during pregnancy

View on the News

IOM’s weight-gain target may be too high

The results reported by Dr. Redman from the MomEE study showed that women with obesity need not ingest surplus calories to gain weight during pregnancy. The findings indicate that pregnant women efficiently convert a portion of their accumulated fat mass to fat-free mass in the form of the fetus, uterus, blood volume, and other tissue. A deficit of about approximately 100 kcal/day effectively kept weight gain within the 11- to 20-pound target recommended by the Institute of Medicine in 2009.

But the weight gains recommended for women with obesity may be too high. The desire of the writers of the IOM recommendation to avoid negative perinatal outcomes for infants may instead lead to negative maternal outcomes, such as preeclampsia, gestational hypertension, and need for cesarean birth. Gestational weight gains below what the IOM recommended for women with obesity may be able to serve present-day standards and work better for these pregnant women by reducing their morbidity risk. Future studies should take into careful account overall nutrient values rather than just calorie intake, as well as physical activity.

The MomEE results showed that a striking two-thirds of women with obesity gained an excess of weight during pregnancy, beyond the 2009 recommendations. This finding highlights the need to identify strategies that can prevent excessive weight gain. Furthermore, results from several studies and systematic reviews suggest that the IOM recommendation for weight gain during pregnancy is too high for women with obesity, especially those with class II-III obesity, with a body mass index of 35 kg/m2 or greater. In my opinion, an appropriate weight-gain target to replace the current, blanket recommendation of 11-20 pounds gained for all women with obesity is a target of 5-15 pounds gained for women with class I obesity, less than 10 pounds for class II obesity, and no change in prepregnancy weight for women with class III obesity.

Sarah S. Comstock, PhD, is a nutrition researcher at Michigan State University, East Lansing. She is an inventor named on three patents that involve nutrition. She made these comments in an editorial that accompanied the MomEE report (J Clin Invest. 2019;129[11]:4567-9).



– Contrary to current U.S. dietary recommendations for pregnancy, women with obesity should not increase their energy intake during pregnancy to achieve the current recommended level of gestational weight gain, based on findings from an intensive assessment of 54 women with obesity during weeks 13-37 of pregnancy.

Dr. Leanne M. Redman, director, Reproductive Endocrinology and Women’s Health Laboratory at the Pennington Biomedical Research Center, Baton Rouge, La. Mitchel L. Zoler/MDedge News

Dr. Leanne M. Redman

To achieve the gestational weight gain of 11-20 pounds (5-9.1 kg) recommended by the Institute of Medicine, women with obesity ‒ those with a body mass index of 30 kg/m2 or greater ‒ had an average energy intake during the second and third trimesters of 125 kcal/day less than their energy expenditure, Leanne M. Redman, PhD, said at a meeting presented by the Obesity Society and the American Society for Metabolic and Bariatric Surgery.

However, women in the study who had inadequate gestational weight gain had a daily calorie deficit that was only slightly larger, an average of 262 kcal/day below their energy expenditure. As a consequence, Dr. Redman believes the take-home message from her findings is that pregnant women with obesity should maintain their prepregnancy energy intake, though she also strongly recommended improvements in diet quality.

“Chasing a 100-kcal/day deficit in intake is extremely problematic,” Dr. Redman admitted, so she suggested that women with obesity be advised simply to not increase their calorie intake during pregnancy.

“The message is: Focus on improving diet quality rather than increasing calories,” she said in an interview. Pregnant women with obesity “do not need to increase calorie intake. They need to improve their diet quality,” with increased consumption of fruits and vegetables, said Dr. Redman, a professor and director of the Reproductive Endocrinology and Women’s Health Laboratory at Louisiana State University’s Pennington Biomedical Research Center in Baton Rouge.

The results she reported represent “the first time” researchers have examined energy expenditure and weight-gain trajectories in women with obesity throughout the second and third trimesters. Until now, dietary energy recommendations for women with obesity during pregnancy were based on observations made in women without obesity.

Those observations led the Institute of Medicine to call for a recommended pregnancy weight gain of 11-20 pounds in women with obesity, as well as gains of 25-35 pounds in women with a normal body mass index of 18.5-24.9 kg/m2 (Weight Gain During Pregnancy: Reexamining the Guidelines; May 2009). In that 2009 document, the IOM committee said that, in general, pregnant women should add 340 kcal/day to their prepregnancy intake during the second trimester and add 452 kcal/day during the third trimester without regard to their prepregnancy body mass index, a recommendation that clinicians continued to promote in subsequent years (Med Clin North Amer. 2016;100[6]:1199-215), and that was generally affirmed by the American College of Obstetricians and Gynecologists in 2013 and reaffirmed in 2018.*

The new evidence collected by Dr. Redman and associates “challenges current practice and argues that women with obesity should not be advised to consume additional energy during pregnancy as currently recommended,” they wrote in an article with their findings published a few days before Dr. Redman gave her talk (J Clin Invest. 2019;129[11]:4682-90).

The MomEE (Determinants of Gestational Weight Gain in Obese Pregnant Women) study enrolled 72 women with obesity during the first trimester of pregnancy and collected complete data through the end of the third trimester from 54 women. The researchers collected data on weight, body fat mass, and energy expenditure at multiple times during the second and third trimesters and calculated energy intake.

Based on body weights at the end of the third trimester, the researchers divided the 54 women into three subgroups: 10 women (19%) with inadequate weight gain by the IOM recommendations, 8 (15%) who had the IOM’s recommended weight gain of 11-20 pounds, and 36 women (67%; total is greater than 100% because of rounding) with excess weight gain, and within each group, they calculated the average level of energy intake relative to energy expenditure.

In addition to the daily calorie deficits associated with women who maintained recommended or inadequate weight, the researchers also found that women with excess weight gain averaged 186 more kcal/day than required to meet their daily energy expenditure.

The analyses showed that the increased energy demand of pregnancy and the fetus is compensated for by mobilization of the maternal fat mass in women with obesity, and that an imbalance between energy intake and expenditure is the main driver of weight gain during pregnancy. The results also highlighted how often pregnant women with obesity fail to follow a diet that results in the recommended weight gain of 11-20 pounds. In the MomEE cohort, two-thirds of enrolled women had excess weight gain.

The finding that women had the recommended weight gain on a diet that cut their daily calorie intake by about 100 kcal/day during the last two trimesters highlighted the nutritional challenge faced by women with obesity who are pregnant. “About three-quarters of women in the study had poor diet quality. There is an opportunity to improve diet with more fruits and vegetables to increase fullness, and [to reduce] energy-dense foods,” Dr. Redman said.

She is planning to collaborate on a study that will test the efficacy and safety of providing pregnant women with extreme obesity (class II-III) with defined meals to provide better control of energy intake and nutritional quality. Dr. Redman said she also hoped that the new findings she reported would be taken into account by the advisory committee assembled by the Department of Health & Human Services and the Department of Agriculture, which are currently preparing a revision of U.S. dietary guidelines for release in 2020.

The National Institutes of Health and the Clinical Research Cores at Pennington Biomedical Research Center funded the study. Dr. Redman had no disclosures.

SOURCE: Redman LM et al. Obesity Week 2019, Abstract T-OR-2079.

*This article was updated 2/7/2020.

Next Article: