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    Obesity Carries Pregnancy Risks

    Obese Women More Likely to Have Babies With Birth Defects, Study Shows

    Obesity & Birth Defects: Results continued...

    The definitions of overweight and obese differed somewhat from study to study, but many studies used those set by the World Health Organization -- a body mass index or BMI of 25 and above for overweight and 30 and above for obese.

    More research is needed to determine if the link between excess weight and birth defects holds for overweight women. "There isn't the same amount of research evidence for overweight as there is for obesity,'' Rankin says.

    Obesity & Birth Defects: Explaining the Link

    Exactly how obesity increases birth defect risk isn't known, but the researchers offer possible explanations.

    • Because maternal diabetes is known to increase the risk of birth defects, and obese women are at higher risk for type 2 diabetes, the mother-to-be may have undiagnosed diabetes.
    • Obese women have been shown to have nutritional deficiencies, especially reduced levels of folate, which is important to prevent neural tube defects. Obese women may need more than the amount routinely recommended to prevent birth defects.

    Obesity & Birth Defects: Other Opinions

    The new review further confirms what physicians have known for a long time, says Sina Haeri, MD, a clinical instructor of maternal-fetal medicine and a fellow at the University of North Carolina at Chapel Hill School of Medicine.

    The problem with some of the previous studies, he tells WebMD, is that they had some methodological weaknesses. "So we took it all with a grain of salt," says Haeri, who recently reported that teen moms who are obese are more likely to be diagnosed with diabetes during the pregnancy (gestational diabetes) and to have cesarean deliveries.

    In the new analysis, he says, the U.K. researchers took all the smaller studies and looked at them together and still found the obesity and birth defects link.

    The new analysis confirms in a convincing way what physicians have been observing and studies have been suggesting for a few years, says Peter Bernstein, MD, a maternal-fetal medicine specialist at Montefiore Medical Center and Albert Einstein College of Medicine, New York.

    Obesity & Birth Defects: Preconception Counseling

    Women who are obese should have preconception counseling to minimize the risks of their excess weight to the newborns, Rankin says.

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