Hormonal Contraceptive Use Among HIV-Positive Women and HIV Transmission Risk to Male Partners, Zambia, 1994–2012

Background. Evidence on the association between female-to-male human immunodeficiency virus (HIV) transmission risk and hormonal contraception is sparse and conflicting. Methods. Heterosexual HIV-discordant couples from Lusaka, Zambia, were followed longitudinally at 3 month-intervals from 1994 to 2012. The impact of hormonal contraception on time to HIV transmission from HIV-positive women to their HIV-negative male partners (M−F+) was evaluated. Results. Among 1601 M−F+ couples, 171 genetically linked HIV transmissions occurred in men over 3216 couple-years (5.3 transmissions/100 couple-years; 95% confidence interval [CI], 4.5–6.2). In multivariable Cox models, neither injectable (adjusted hazard ratio [aHR], 0.6; 95% CI, .4–1.2), oral contraceptive pill (aHR, 0.8; 95% CI, .3–2.1), nor implant (aHR, 0.8; 95% CI, .5–1.4) use was associated with HIV transmission, relative to nonhormonal methods, after controlling for the man's age at baseline and time-varying measures of pregnancy, self-reported unprotected sex with the study partner, sperm present on a vaginal swab wet mount, genital inflammation of either partner, genital ulceration of the man, and first follow-up interval. Sensitivity analyses, including marginal structural modeling and controlling for viral load and fertility intentions available in a subset of couples, led to similar conclusions. Conclusions. Our findings suggest null associations between hormonal contraception and risk of female-to-male HIV transmission. We support efforts to increase the contraceptive method mix for all women, regardless of HIV serostatus, along with reinforced condom counseling for HIV-serodiscordant couples.