News: Injectable contraceptives cause bone loss

After 2 years, adolescent girls using depot medroxyprogesterone acetate (DMPA) as their form of contraception had lower bone mineral density (BMD) determinations at the spine and femoral neck than girls using oral contraceptives (OCs) or neither forms of birth control, according to the results of an observational, prospective, cohort study.

Researchers included 433 postmenarcheal girls between the ages of 12 and 18 years. Over 2 years, mean percentage change in spine BMD for girls taking DMPA, OCs, or neither was –1.5%, +4.2%, and +6.3%, respectively. Mean percentage change in BMD at the femoral neck was –5.2%, +3.0%, and +3.8%, respectively.

Most of the decrease in BMD seen with DMPA occurred during the first year of use and then slowed during the second year. Decreases in BMD never approached a range consistent with osteopenia.