Bone mineral density at various anatomic bone sites in women receiving combined oral contraceptives and depot-medroxyprogesterone acetate for contraception

Abstract

The association between users of combined oral contraceptives and depot-medroxyprogesterone acetate (DMPA) for contraception and bone mineral density (BMD) has been controversial because of variations among studies. Like other studies, this cross-sectional study compares BMD in users of combined oral contraceptives and DMPA with that in nonusers. Unlike previous studies, we defined long-term use as >2 years, and we measured more bone sites than previous studies including lumbar spines, femurs, and forearms. The study group consisted of 59 women aged 30 years to 34 years who had been using combined oral contraceptives for 57.36 +/- 27.02 months with a minimum period of 24 months, 34 women of the same age who had been using DMPA as contraceptive for 55.76 +/- 35.31 months, and 62 women of the same age who had not used any steroid hormonal contraceptives for more than 6 months. BMD was measured by dual energy photon absorptiometer at lumbar spine 2-4, neck of femur, Ward's triangle of femur, greater trochanter of femur, ultradistal radius, and distal ulnar, respectively. Age, body mass index, and lifestyles of both groups were matched with nonusers. Mean BMD at lumbar spine (L2-4) in the DMPA users was significantly lower than in the controls (1.031 +/- 0.090 vs. 1.096 +/- 0.116, p = 0.007). There were no significant differences in BMD values at bone sites other than lumbar spine between DMPA users and the controls. There were no significant differences in BMD values at all bone sites between combined oral contraceptives users and the controls. We conclude that combined oral contraceptives are not associated with changes in values of BMD, while DMPA is associated with decreased BMD only at lumbar spine. We comment that steroid hormonal contraceptives are safe to use for long-term contraception regarding bone mass effects.