Objective: To examine bone density among adolescents receiving different forms of hormonal contraception along with that of control subjects.
Methods: Baseline and 1-year measures of lumbar vertebral bone density were obtained in girls receiving depot medroxyprogesterone acetate (Depo-Provera) (n = 15), levonorgestrel (Norplant) (n = 7), or oral contraceptives (n = 9) and in girls receiving no hormonal treatment (n = 17). In a subsample of Depo-Provera users (n = 8), Norplant users (n = 3), and control subjects (n = 4), bone density measurements were repeated after 2 years. Bone density was measured by dual-energy x-ray absorptiometry.
Results: Body mass indexes, level of pubertal development, substance use, and reproductive histories were not significantly different among the groups. More black girls were represented in the initial Depo-Provera group (p < 0.02), girls in the Norplant group exercised more hours per week (p < 0.02), and control subjects were older (p < 0.01) than those in the other groups. These variables did not significantly affect bone density results. After 1 year, bone density decreased 1.5% in Depo-Provera users, compared with increases of 2.5% in Norplant users, 1.5% in oral contraceptive users, and 2.9% control subjects (p < 0.02). After 2 years, bone density increased a total of 9.3% in Norplant users and 9.5% in control subjects but decreased a total of 3.1% in Depo-Provera users (p < 0.0001).
Conclusion: These data suggest that Depo-Provera may, at least temporarily, suppress the expected skeletal bone mineralization in adolescents, whereas Norplant and oral contraceptives are associated with the expected increase in bone density in this population.
PIP: In Ohio, data on 31 postmenarcheal women, 12-21 years old and using hormonal contraception (Norplant = 7, Depo Provera = 15, and oral contraceptives [OCs] = 9) were compared with data on 17 controls of similar age to prospectively examine lumbar bone density in girls before and after 1 and 2 years of hormonal contraceptive use and to compare the results with young women not using hormonal contraceptives. The subjects attended a general adolescent clinic at Children's Hospital in Columbus. There was an insufficient number of OC users at 2 years, so they were not included in second year analyses. Initial height and weight were significantly associated with bone density values (p 0.05). Weight accounted for the most variance both at baseline (p 0.001) and after 1 year of treatment (p 0.01). At baseline and 1 year, bone density values between patient groups were not significantly different. At 2 years, however, Norplant users had higher bone density than Depo- Provera users and controls (1.308 vs. 1.004 and 1.087, respectively; p 0.01). After 1 year, Depo-Provera users experienced a decrease (1.53%) in bone density while Norplant users, OC users, and controls experienced an increase in bone density (2.46%, 1.52%, and 2.85%, respectively). The change in bone density between Depo-Provera users and controls was significant (p 0.02). At 2 years, Depo Provera users experienced a decrease in bone density while Norplant users and controls experienced an increase (-3.12% vs. 9.33% and 9.49%, respectively; p 0.0001). This study is important because 50% of adult bone mass is accrued during adolescence. In fact, bone mass peaks during adolescence. It is not known whether bone loss during Depo Provera use is reversible after treatment discontinuation. These findings show that Depo Provera inhibits skeletal bone mineralization in adolescents, at least temporarily, while Norplant and OCs appear to increase bone density.