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Diet and Exercise May increase Pregnancy Weight, But They Should Start Early

    Abdulaziz Sobh
    By Abdulaziz Sobh

    Categories: Health


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    Overweight women limited their weight gain with a diet and exercise program during pregnancy but did not reduce the rate of complications such as gestational diabetes.

    For years, maternal health experts have worried about a worrying statistic: more than half of pregnant women in the United States are overweight or obese when they conceive, which puts them and their children at higher risk of developing diabetes and other health problems.

    Then, about a decade ago, the federal government launched a multimillion-dollar test to see if diet and exercise could help overweight women maintain a healthy weight during their pregnancies and potentially reduce their rate of complications. On Thursday, the findings were announced and the results were mixed: starting a diet and exercise program at the beginning of her second trimester helped many women avoid excessive weight gain during their pregnancies. But it did not reduce its rate of gestational diabetes, hypertension and other adverse outcomes.

    Experts said the research was encouraging and instructive. He confirmed that overweight and obese women can safely limit weight gain during pregnancy with lifestyle interventions. But it also suggests that to improve the obstetric outcomes and the health of their babies, women who carry an extra weight may need significant changes in their lifestyle before they conceive, said Dr. Alan Peaceman, chief of maternal-fetal medicine at Northwestern Feinberg University. School of Medicine and the principal investigator of the study, which was published in Obesity.

    "This is a problem that is more important now than ever, and should be addressed," he added. "We're going to have to start talking to women who are overweight or obese even before pregnancy and explain the risk of that weight in a possible pregnancy."

    [Listen to Dr. Peaceman's podcast at B.M.I. and weight gain during pregnancy.]

    The new research comes at a critical moment. Decades ago, health authorities routinely urged pregnant women to gain enough weight to reduce their chances of having low-weight babies. But when the obesity epidemic took off in the 1980s and 1990s, it spared almost no population, including pregnant women. Research conducted by the Centers for Disease Control and Prevention found that the prevalence of obesity among pregnant women increased by 69 percent between 1993 and 2003. Currently, about 26 percent of women are overweight when they enter pregnancy and 25.6 percent are obese, according to the latest CDC data.

    Women in these groups are more likely to exceed the recommended amount of weight gain during pregnancy and to retain that weight after delivery. Among the complications, they are more likely to experience longer labor, abnormally large babies, hypertension, and cesarean deliveries. Obese women also have higher rates of gestational diabetes, spontaneous abortions and premature births. And a series of studies show that their children have increased rates of obesity and type 2 diabetes.

    In 2009, the Institute of Medicine issued a report that describes the number of weight women should gain during their pregnancies based on their body mass index. Women in the normal weight category should increase between 25 and 35 pounds, according to the guidelines, while overweight people should add 15 to 25 pounds. Obese women are encouraged to gain no more than 20 pounds during pregnancy.

    Over the years, a series of studies analyzed whether changes in lifestyle could improve health outcomes for pregnant women with high B.M.I.s. But many of the studies were small, not very rigorous or of poor quality, so the National Institutes of Health set out to finance a comprehensive and definitive study in a diverse group of women. The resulting study recruited 1,150 overweight and obese women in seven clinics across the country and randomly assigned them to a control group or intervention group that followed a variety of diet and exercise strategies. The women were between nine and 15 weeks pregnant when they joined the study.

    The topics included women like Heather Kinion, 39, who lives in Chicago and works for a quilting magazine. Ms. Kinion was a bit overweight when she became pregnant in the fall of 2015. She joined the Northwestern study in her first trimester and was assigned to work with a nutrition coach who told her to follow her food intake with an application of smartphone. Ms. Kinion did not eat more than 2,300 calories per day, replaced soft drinks with tea, and reduced sugary treats such as ice cream, cinnamon rolls, and smoothies. She added more fruits and vegetables to her diet and tried to exercise and walk more.

    Ms. Kinion increased approximately 20 pounds during her pregnancy, which was in the recommended gain and weight gain and had a healthy baby, named Julia, in 2016.

    "It was super effective," he said of the program. "Two weeks after my daughter was born, I had a weight that I think was 10 pounds less than before pregnancy."

    Ultimately, the researchers found that women in the diet and exercise arm of the study gained on average four pounds less than those in the control group. They were 48 percent less likely to exceed the recommended amount of weight gain during pregnancy at the Institute of Medicine.

    However, for most women, the intervention did not work. About 68.6 percent of women in the diet and exercise group exceeded the recommended amount of weight gain, compared to 85 percent of women in the control arm. At the end of the study, the rate of major complications of pregnancy was not different.

    "One of our predominant suspicions is that when we started the intervention at the beginning of the second trimester it was too late," said Dr. Peaceman. "It is possible that adverse outcomes were already influenced by the weight gain before then."

    Dr. Emily Oken, a maternal health expert at Harvard Medical School who was not involved in the research, said future studies could analyze the impact of assigning overweight women to make lifestyle changes before getting pregnant. He also speculated that the average reduction in weight gain that occurred in the new study might not be large enough to have a real impact for many women.

    "It's not clear that these small differences in weight gain cause differences in outcomes for the baby," said Dr. Oken.

    Another expert on maternal health, Dr. Patrick Catalano, said it was clear from other studies that public health efforts should focus on reaching women to help them improve their health long before they become pregnant.

    "My belief is that this has to be a life focus, it can not be something that we deal with when women are already 14 weeks pregnant," said Dr. Catalano, principal investigator of Tufts Medical's Maternal and Child Research Institute. Center. "If you have a normal weight during pregnancy, statistically you have less risk of having many complications, if the goal is to try to improve pregnancy outcomes for both the mother and her offspring, then we should start early."