Menopausal bone loss in long-term users of depot medroxyprogesterone acetate contraception

OBJECTIVE: The purpose of this study was to determine the rate of early postmenopausal bone loss in women who had used depot medroxyprogesterone acetate contraception through to menopause. STUDY DESIGN: Bone mineral density at the lumbar spine and femoral neck was assessed prospectively over 3 years in 15 women who reached a natural menopause and who did not undergo hormone replacement therapy and in 16 long-term users of depot medroxyprogesterone acetate who discontinued depot medroxyprogesterone acetate only on reaching menopause. Of the latter, 5 women subsequently underwent hormone replacement therapy. RESULTS: Early menopausal bone loss was rapid in the control group (6% from both sites over 3 years), but the users of depot medroxyprogesterone acetate (who did not take hormone replacement therapy) showed little change in bone mineral density. Between-group differences were statistically significant at years 2 and 3 at both sites (P <.03-<.002). In the users of depot medroxyprogesterone acetate who underwent hormone replacement therapy, bone mineral density increased significantly (P <.03) at the lumbar spine and was stable at the femoral neck. CONCLUSION: Women who use depot medroxyprogesterone acetate through to menopause have attenuated rates of bone loss from the lumbar spine and femoral neck, presumably because they have already lost the estrogen-sensitive component of bone.