Relationship between weight and bone mineral density in adolescents on hormonal contraception.

Study Objective: Since bone loss has been observed among adolescents on depot medroxyprogesterone acetate (DMPA), a clinical population that commonly experiences weight gain, we were interested in examining the direct relationship between body weight and bone mineral density (BMD) in adolescents on DMPA as compared to those on oral contraceptive pills (OC) or on no hormonal contraception (control).

Design: Prospective, Longitudinal study.

Setting: Four urban adolescent health clinics in a large metropolitan area.

Participants: Postmenarcheal girls, age 12-18 years, selecting DMPA, OC or no hormonal contraception.

Interventions: At baseline, 6, 12, 18, and 24 months, all study participants underwent measurement of weight and BMD of the hip and spine.

Main Outcome Measures: The correlation between weight and BMD, and the correlation between change in weight and change in BMD were assessed at each time point.

Results: Body weight was significantly (P < 0.05) positively correlated with femoral neck BMD and spine BMD at each time point regardless of contraceptive method. Change in body weight at 12 and 24 months was highly correlated with change in femoral neck BMD (P < 0.0001) for all treatment groups. No statistically significant correlation between change in weight and change in spine BMD was seen in the DMPA, OC, or control subjects at 12 or 24 months.

Conclusion: Weight gain on DMPA may mitigate loss of BMD among adolescent users.