Objective: To investigate whether the incidence of HIV infection is higher among sexually active women using depot medroxyprogesterone acetate (DMPA) or noresthisterone enanthate (NET-EN) injections for contraception than among women using nonhormonal or no contraception.
Methods: Five hundred and fifty-one initially HIV-negative women were followed up for a total of 491 person-years. Participants were interviewed, counselled, examined, tested for HIV and other STIs, and treated, at three monthly intervals for 1 year.
Results: There was no significant association between progestin contraceptive use and HIV infection (rate ratio 1.1, 95% CI 0.5 to 2.8; log-rank test, p=.73). In proportional hazards regression, the only significant hazard ratios for HIV acquisition were prevalent Neisseria gonorrhoea (5.2; 95% CI 1.1 to 23.7, p=.035) and Trichomonas vaginalis (4.8; 95% CI 1.0 to 22.8, p=.049); bacterial vaginosis was marginally significant (2.8; 95% CI 1.0 to 8.3, p=.057). The adjusted hazard ratios for NET-EN and DMPA were 1.76 (95% CI 0.64 to 4.84) and 0.46 (95% CI 0.06 to 3.79), respectively, relative to nonuse. Five hundred and twelve of 551 women had one or more confirmed STIs during the study.
Conclusions: There is no evidence of an association between HIV infection and injectable contraceptives. Due to the limited power of this study and because similar studies have not included young women using NET-EN, we recommend that further research be carried out to focus on the use of NET-EN and HIV acquisition in high risk groups.