The effects of injectable hormonal contraceptives on HIV seroconversion and on sexually transmitted infections.

Objectives: To investigate the association between hormonal contraceptives and risk of HIV-1 seroconversion and prevalence of other sexually transmitted infections.

Design: Prospective cohort.

Methods: The study population was 2,236 HIV-negative women who were screened in a biomedical intervention trial in Durban, South Africa. The association between the use of hormonal contraceptives and risk of HIV-1 seroconversion was modeled using Cox proportional hazards regression analysis. Prevalence of Chlamydia trachomatis and Neisseria gonorrhoeae infections were assessed using logistic regression models.

Results: Hormonal injectables were the most common method of contraceptives (46.47%) followed by condom use (28.04%). Overall, compared with women who reported using condoms or other methods as their preferred form of contraceptive, those who reported using hormonal contraceptives (injectables and oral pills) were less likely to use condoms in their last sexual act. Using hormonal injectables during the study was significantly associated with increased risk for HIV-1 infection [adjusted hazard ratio 1.72, 95% confidence interval (CI) 1.19-2.49, P = 0.005]; hormonal injectables were also significantly associated with higher prevalent of C. trachomatis infections (adjusted odds ratio 2.46, 95% CI 1.52-3.97, P < 0.001).

Conclusion: Hormonal injectables are highly effective and well tolerated family planning methods and have played an important role in reducing unplanned pregnancies and maternal and infant mortality. However, they do not protect against HIV-1 and other sexually transmitted infections. This study reinforces the importance of comprehensive contraceptive counseling to women about the importance of dual protection, such as male condoms and hormonal contraceptives use.