摘要Background Depot medroxyprogesterone acetate (DMPA) as a hormonal contraceptive is highly effective and widely used,but it may reduce bone mineral density (BMD) and increase the risk of osteoporosis.We compared BMD between users of intramuscular DMPA and nonhormonal subjects.Methods The study included 102 women aged between 16 and 18 years using DMPA for 24 months and 97 women aged between 16 and 18 years using nonhormonal contraception as nonusers control group.BMD of the lumbar spine and femoral neck was measured every 12 months for 24 months using dual-energy X-ray absorptiometry,comparing mean BMD changes in DMPA users and nonusers.Results There were no significant differences between groups at baseline in age,gynecologic age,body mass index (BMI),lumbar spine BMD and femoral neck BMD,etc.At 24 months of DMPA treatment,the mean percentage change from baseline in lumbar spine and femoral neck BMD values had decreased by 1.88％ and 2.32％,respectively.The mean lumbar spine and femoral neck BMD in DMPA group at 24 months were not significantly different compared to baseline (P=-0.212 and P=0.106,respectively).In comparison,in nonhormonal control group,there was a trend toward increasing BMD.At 24 months of observation,the mean percentage change from baseline in lumbar spine and femoral neck BMD had increased by 2.08％ and 1.46％,respectively.There were no significant difference compared to baseline (P=-0.160 and P=-0.288,respectively).Mean BMD at the spine and femoral neck did not differ significantly between DMPA users and nonusers over 12-month,but the BMD values at both anatomical sites were significantly lower in DMPA users compared with nonusers after 24-month treatment (P=-0.009 and P=-0.009,respectively).Conclusion The evidence of our study suggested that the use of DMPA for short-term (＜12-month) has no significant effects on BMD at spine and femoral neck,but long-term exposure to DMPA may prevent the bone mass accrual in adolescents.