Purpose: To conduct a longitudinal comparison of bone mineral density (BMD) in 370 adolescent girls, aged 12-18, who self-selected depot medroxyprogesterone acetate (DMPA) or an oral contraceptive (OC) containing 20 microg ethinyl estradiol/100 microg levonorgestrel with that in girls who received no hormonal treatment (control group).
Methods: Lumbar spine and femoral neck BMD measurements were obtained by dual energy x-ray absorptiometry at baseline and 12 months. Data were analyzed with repeated measures analysis of covariance methods.
Results: Over 12 months, lumbar spine BMD decreased in the DMPA group (n = 29), with a mean percent change of -1.4% (95% confidence interval [CI] -2.73, -0.10), and increased by a mean of 3.8% (95% CI 3.11, 4.57) in the control group [n = 107 (p < .001)]. The increase in mean percent change in lumbar spine BMD in the OC group (n = 79), 2.3% (95% CI 1.49, 3.18), was significantly smaller than in the control group (p = .03). Over 12 months, the mean percent change in femoral neck BMD was -2.2% (95% CI -3.95, -0.39) in the DMPA group, but increased 2.3% (95% CI 1.29, 3.27) in the control group (p < .001). The increase in mean percent change at the femoral neck in the OC group, 0.3% (95% CI -0.87, 1.41), was significantly lower than in the control group (p = .03).
Conclusions: Our study contributes to an increasing body of knowledge indicating a negative impact of DMPA on bone health in young women. Additional findings suggest a potential adverse effect of an OC containing 20 microg ethinyl estradiol/100 microg levonorgestrel on bone health in adolescents.