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New Study Finds Breast Cancer Survivors Don’t Need to Increase Fruits and Vegetables beyond National Guidelines

Kaiser Permanente’s Center for Health Research 2007 Saward Lecture

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Making longer-term lifestyle changes lowers rates of high blood pressure and risk of heart disease

What's New - Hip Fracture Risk

Women who didn't have children have a 44 percent greater risk of hip fractures

Child Bearing Reduces Risk of Hip Fractures Later in Life

((PORTLAND, Ore.) – A new study conducted at Kaiser Permanente's Center for Health Research shows that women who have never given birth to a child have a 44 percent greater risk of hip fractures when they become elderly than women who did have children. The researchers also found that, among women who had a child, each additional birth reduced their hip fracture risk by nine percent. Results of the study will appear in the May issue of the Journal of Bone and Mineral Research.

These findings are from the Study of Osteoporotic Fractures (SOF), which is funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Institute on Aging. SOF began in 1986 and is the largest long-term observational study of risk factors for osteoporosis fractures ever conducted. Nearly 10,000 postmenopausal women age 65 or older are participating in the study at clinical centers located in Portland, Oregon; Minneapolis, Minnesota; Pittsburgh, Pennsylvania; and Baltimore, Maryland. Almost 200 scientific articles based on SOF data have been published to date. National screening guidelines for osteoporosis are largely based on SOF findings.

"We expect these new findings will be very important to women who have never had a child," says lead author Teresa Hillier, MD, an endocrinologist and principal investigator for SOF at the Center for Health Research. "We do not expect women will alter their childbearing choices based on these findings. However, we hope that women who choose not to have a child or cannot have a child will see their physicians to assess their risk factors and find out what kinds of preventive actions they should take. We have long known that not having a child increases a woman's risk for breast cancer. Now that we know it also increases the risk for osteoporosis, prevention is more important than ever."

The study also found that the increased risk of hip fracture is not related to bone mineral density levels - both groups of women had nearly identical measurements on this.

"This finding really surprised us," says Dr. Hillier, "because measuring bone mineral density is how we screen for osteoporosis. We expected that since childbearing reduces osteoporosis risk, it must also be associated with higher bone mineral density. The fact that women who have not given birth to children have the same density levels as women who have had children means that physicians will not be able to rely on measuring bone mineral density to assess a childless woman's future risk of hip fracture. This means that it is important for a childless woman approaching menopause to discuss with her physician ways of reducing her risk of osteoporosis."

The study found that the two groups of women had similar rates of wrist fractures and that women who did not have children had slightly higher rates of spinal fractures than women who had children. The researchers also investigated a wide range of other possible factors that are known to affect risk of hip fracture in both groups of women. These factors include age, weight, height at age 25, maternal history of hip fracture, fracture of any bone after age 50, self-reported health, physical activity, history of diabetes, current calcium intake, current estrogen use, and pulse rate. None of these factors was found to alter the results.

"What we know is that having children reduces women's risk of hip fractures," says Hillier. "What we don't know is why. One possibility is that the changes in hip and pelvic alignment that take place during pregnancy and childbirth could permanently alter hip and bone structure and protect women from future hip fractures. Whatever the cause or mechanism, what's most important is our finding of increased risk of hip fracture in women who have not had children irrespective of their bone mineral density."

Kaiser Permanente's Center for Health Research, founded in 1964, is a not-for-profit research institution conducting research in the public interest. Its mission is to advance knowledge to improve health. Kaiser Permanente Northwest is a group practice health care organization serving the health care needs of more than 450,000 people in Northwest Oregon and Southwest Washington.

For more infomation contact:
Terry Fitzpatrick (503) 335-6602 or
Jim Gersbach (503) 831-4820

Released: April 21, 2003