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Press Releases: National

October 31, 2008

Gaining Too Much Weight During Pregnancy Nearly Doubles Risk of Having A Heavy Baby

Heavy babies have more birth complications; they are also more likely to become overweight or obese children and adults

Portland, Ore. – A study by the Kaiser Permanente Center for Health Research of more than 40,000 women and their babies found that women who gained more than 40 pounds during their pregnancies were nearly twice as likely to have a heavy baby. Published in the November issue of Obstetrics & Gynecology, the study found that more than one in five women gains excessive weight during pregnancy, doubling her chances of having a baby that weighs 9 pounds or more.

"Too many women gain too much weight during pregnancy. This extra weight puts them at higher risk for having heavy babies, and these babies are programmed to become overweight or obese later in life," said study lead author Teresa Hillier, MD, MS, an endocrinologist and senior investigator at the Kaiser Permanente Center for Health Research in Oregon and Hawaii. "A big baby also poses serious risks for both mom and baby at birth – for mothers, vaginal tearing, bleeding, and often C-sections, and for the babies, stuck shoulders and broken collar bones."

While researchers have known for some time about the link between diabetes during pregnancy and heavier birth weights, and recently have learned how maternal weight gain affects the birth weight, this is the first study to determine that women who gain excessive weight are even more likely to have heavy babies than women who are treated for gestational diabetes.

"This is one more good reason to counsel women to gain the ideal amount of weight when they are pregnant," said study co-author Kim Vesco, MD, MPH, an obstetrician and gynecologist with Kaiser Permanente in Portland, Ore. "From a practical standpoint, women who gain too much weight during pregnancy can have a very difficult time losing the weight after the baby is born."

The study followed 41,540 women who gave birth in Washington, Oregon and Hawaii from 1995-2003. More than 20 percent of the women who gained more than 40 pounds – which is the maximum recommended pregnancy weight gain – gave birth to heavy babies. In contrast, less than 12 percent of women with normal weight gain had heavy babies.

At greatest risk were the women who gained more than 40 pounds and also had gestational diabetes; nearly 30 percent of them had heavy babies. That risk was significantly reduced – to only 13 percent – when women with gestational diabetes gained less than 40 pounds.

"The take-home message is that all pregnant women need to watch their weight gain, and it is especially important for women who have risk factors like gestational diabetes," Dr. Hillier said.

The study was funded by a grant from the American Diabetes Association. Authors include Teresa Hillier, MD, MS; Kathryn L. Pedula, MS; and Kimberly K. Vesco, MD, MPH, from the Kaiser Permanente Center for Health Research in Portland; Mark M. Schmidt, BA, and Judith A. Mullen, APRN, from the Kaiser Permanente Center for Health Research in Hawaii; Erin S. LeBlanc, MD, MPH, from Oregon Health & Science University; and David J. Pettitt, MD, from the Sansum Diabetes Research Institute in Santa Barbara, Calif.

About the Kaiser Permanente Center for Health Research
Kaiser Permanente's Center for Health Research, founded in 1964, is a nonprofit research institution dedicated to advancing knowledge to improve health. It has research sites in Portland, Ore., Honolulu, Hawaii, and Atlanta.

About Kaiser Permanente Research
Kaiser Permanente's eight research centers comprise one of the largest research programs in the United States and engage in work designed to improve the health of individuals everywhere. KP HealthConnect™, Kaiser Permanente's electronic health record, and other resources provide population data for research, and in turn, research findings are fed into KP HealthConnect to arm physicians with research and clinical data. Kaiser Permanente's research program works with national and local health agencies and community organizations to share and widely disseminate its research data. Kaiser Permanente's research program is funded in part by Kaiser Permanente's Community Benefit division, which in 2007 directed an estimated $1 billion in health services, technology, and funding toward total community health.

About Kaiser Permanente
Kaiser Permanente is committed to helping shape the future of health care. We are recognized as one of America’s leading health care providers and not-for-profit health plans. Founded in 1945, our mission is to provide high-quality, affordable health care services and to improve the health of our members and the communities we serve. We currently serve 8.6 million members in nine states and the District of Columbia. Care for members and patients is focused on their total health and guided by their personal physicians, specialists and team of caregivers. Our expert and caring medical teams are empowered and supported by industry-leading technology advances and tools for health promotion, disease prevention, state-of-the art care delivery and world-class chronic disease management. Kaiser Permanente is dedicated to care innovations, clinical research, health education and the support of community health. For more information, go to: www.kp.org/newscenter.