Bone-sparing properties of oral contraceptives

Postmenopausal osteoporosis is a major health care problem that affects 20 million women in the United States and accounts for >1 million fractures per year. Hormone replacement therapy is effective for reducing bone loss in the postmenopausal women. However, intervention before menopause may delay or prevent the decline in bone mass that begins between ages 30 and 40 years. The effects of oral contraceptives on bone mass have been investigated, and a positive association between oral contraceptive use and bone mass that is directly related to the duration of oral contraceptive use was observed. The effects of oral contraceptives on bone mass may be related to the specific formation. The effect of estrogens is dose related, and the optimal dose appears to be 25 to 35 μg of ethinyl estradiol or its equivalent. Results from several studies show that norethindrone has a positive effect on bone mass. An oral contraceptive may offer optimal birth control for the older premenopausal woman who currently uses other forms of birth control. (AM J OBSTET GYNECOL 1996;174:15-20.)