Prospective study of hormonal contraception and women's risk of HIV infection in South Africa

Abstract

Background Many women using hormonal contraceptives are also at risk of sexually transmitted HIV infection, but data are mixed on whether hormonal contraception increases women's risk of HIV. We investigated associations between HIV incidence and use of combined oral contraceptives (COC), norethindrone enanthate (NET-EN) or depot medroxyprogesterone acetate (DMPA) in a cohort of South African women. Methods Participants were 4200 HIV-negative women aged 35–49 years enrolled into a cervical cancer screening trial. At enrollment, women were tested for sexually transmitted infections and reported on their sexual behaviour and contraceptive use. During the 24 months of follow-up, women reported on their sexual behaviours and contraceptive use and underwent repeat HIV testing. Results During the 5010 person-years of follow-up, 111 incident HIV infections were observed (HIV incidence, 2.2 infections/100 person-years). At enrollment, 21% of women reported using hormonal contraception, primarily DMPA (14% of all women) or NET-EN (5%). After adjusting for sexual risk behaviours and sexually transmitted infections, the incidence of HIV was similar among women using COC, NET-EN or DMPA compared with women not using any hormonal method [incidence rate ratios and 95% confidence intervals, 0.65, 0.16–2.66; 0.79, 0.31–2.02 and 0.96, 0.58–1.59, respectively]. There was also no association between increased duration of DMPA use and HIV incidence (P-value for trend, 0.51). Conclusions These findings contribute to the evidence from general population cohorts of women that hormonal contraceptive use is not associated with increased risk of HIV acquisition. Nonetheless, family planning services are an important venue for HIV prevention activities.