Objective: To compare longitudinal changes in bone mineral density (BMD) among first-time depot medroxyprogesterone acetate (DMPA) users to women using no hormonal contraception, and evaluate user characteristics associated with that BMD change. Design: Prospective longitudinal study. Setting: Healthy volunteers in an academic research environment. Patient(s): Women, aged 18 to 35, choosing DMPA for contraception (n = 178) and women using no hormonal contraception (n = 145). Main Outcome Measure(s): Hip and spine BMD measured, at three-month intervals for 24 months, by dual energy x-ray absorptiometry. Result(s): Mean hip BMD declined 2.8% (SE = 0.034) 12 months following DMPA initiation and 5.8% (SE = 0.096) after 24 months. Mean spine (L1-L3) BMD declined 3.5% (SE = 0.022) and 5.7% (SE = 0.034), respectively, after one and two years of DMPA use. Mean hip and spine BMD of control participants changed less than 0.9% over the same period. Among DMPA users, body mass index (BMI) change was inversely associated with BMD change at the hip, but not at the spine. Calcium intake, physical activity, and smoking did not influence BMD change in either group. Conclusion(s): Hip and spine BMD declined after one DMPA injection and this decline continued with each subsequent injection for 24 months. With the exception of increasing BMI among DMPA users, no user characteristics offered protection against DMPA-related BMD loss. (C) 2004 by American Society for Reproductive Medicine.
Available at: http://works.bepress.com/m_clark/28/