Abstract
PURPOSE: To determine whether depot medroxyprogesterone acetate (DMPA) use is associated with an increased risk of acquisition of sexually transmitted infections (STIs) in a cohort of healthy adolescents, for whom prospective evidence is sparse. METHODS: Adolescent women aged 14-17 years (n = 342) were recruited from clinical sites in the United States between 1999 and 2005. They returned quarterly for interviews and STI testing. During alternating 3-month periods, participants also completed daily diaries of sexual behaviors and performed weekly vaginal self-obtained swabs to test for STIs. Data collected through 2009 (median follow-up length = 42.2 months) were analyzed. Univariable and multivariable tests of association between STI acquisition during the 3-month diary period and covariates were calculated, using nonlinear mixed-effect logistic regression models to control for repeated measurements. RESULTS: In multivariable analysis, there were no significant associations between DMPA use in the current or previous 3-month period and incidence of Chlamydia trachomatis, Neisseria gonorrhoeae, or Trichomonas vaginalis. The number of total or unprotected sexual events during the diary period was not associated with the risk of STI. Older age was a protective factor for the development of Chlamydia trachomatis (odds ratio = .85; 95% confidence interval = .76-.96). The only factor significantly associated with an increased risk of contracting all three STIs was a greater number of sexual partners during the diary period (odds ratio, range = 1.91-2.62). CONCLUSIONS: In this U.S.-based cohort of adolescent women, we found no evidence that DMPA use was associated with increased STI risk. Efforts to curb STI transmission among adolescents should focus on education about the reduced number of sexual partners.