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Hormonal Contraception Doubles HIV Risk

4 October 2011

"Women at the maternity clinic in Kabgayi, Rwanda" by Joshua Treviño, shared with cc license via Flickr

Yesterday The New York Times reported on research findings that show an injectable contraceptive can double the risk of acquiring HIV. The research design was a prospective cohort study, meaning it followed a similar group of people over time and compared their outcomes with respect to the difference under study (in this case, whether or not the female partner used hormonal contraception). The analysis relied on 1314 serodiscordant couples, drawn from two longitudinal studies being conducted in seven countries in East and Southern Africa (Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda, and Zambia). The study was published in Lancet Infectious Diseases (gated). Technically, the study reported hormonal contraception (including both oral pills and injectables) doubled HIV risk for both men and women, but the findings are only statistically significant for injectable contraceptives. Here are a few excerpts about the results (warning: very technical language ahead!):

Rates of HIV-1 acquisition were higher in women using hormonal contraception than in those who were not (table 3 [not shown in this blog post]). In multivariate Cox proportional hazards analysis adjusted for age, pregnancy, unprotected sex, and concentrations of plasma HIV-1 in HIV-1-infected partners, use of hormonal contraceptives was associated with a two times increased risk of HIV-1 acquisition (adjusted hazard ratio 1·98, 95% CI 1·06–3·68). Increased risk was reported for both injectable (adjusted hazard ratio 2·05, 95% CI 1·04–4·04) and oral contraceptive use (1·80, 0·55–5·82), although the analysis of oral contraceptive use included only 50·5 person-years and was not statistically significant.

The rate of HIV-1 transmission from women using hormonal contraceptives to their male partners was higher than was the rate of transmission from women who did not use hormonal contraceptives (table 4 [not shown in this blog post]). In multivariate analysis adjusted for age, pregnancy, unprotected sex, and concentrations of plasma HIV-1 in HIV-1-infected partners, men’s HIV-1 risk was increased two times when their partners were using hormonal contraception (adjusted hazard ratio 1·97, 95% CI 1·12–3·45; table 4). Both injectable and oral contraceptive use by female partners were associated with increased HIV-1 risk for men, although the effect was significant only for injectable contraception (table 4 [not shown in this blog post]).

The study has a number of implications. I will focus on just one: what will have to change in the healthcare system to implement a shift in the contraception being promoted? The surge in use of injectables has been seen as a promising advance in family planning in Africa, where fertility rates are high. In Malawi, for example, between 1992 and 2008, contraceptive use rose from 7% to 39% of married women. This increase is largely due to increased use of injectable contraceptives: from 1.5% in 1992 to 29% in 2008 (source). The increased use of contraception has been associated with the decentralization of health services — instead of relying on the very few doctors in a country to provide family planning (including complicated procedures like sterilization or tubal ligation), nurses and community health workers have been distributing injectables, the pill, and other contraceptive measures. In a context where HIV prevalence is high (Malawi’s HIV prevalence is 12%, 9th highest in the world), there is a need to find alternative family planning solutions for women who have relied on injectable contraceptives. One might suggest promoting condom use (condom distribution also occurs at the lower levels in the health workforce), but the social significance of proposing condom use to a partner is a serious barrier. (Injectables, on the other hand, could be taken without the partner even knowing.) There were too few women who reported using intrauterine devices for contraception (which can be provided by nurses) to know if they too have any impact on HIV acquisition/transmission, so it is unclear if diverting women from injectables to IUDs is a tenable solution. Especially if we believe that family planning is not just in the best interest of women, but also imperative for poverty reduction, the countries hardest hit by HIV — some are the world’s poorest — have a huge challenge ahead of them.

3 Comments leave one →
  1. jimiadams permalink
    7 October 2011 11:00 am

    Now, i’m no biologist/virologist, but now that i read this more closely i’m particularly puzzled by the fact that the increase was approximately double in *both* directions. i’m having a hard time coming up with a plausible mechanism for injectable contraception to increase susceptibility *and* infectivity. Am i off my rocker here? Is there something obvious i’m missing?

    • Monica permalink
      20 October 2011 9:04 pm

      It has long been known that injectable contraceptions thin the vaginal wall of monkeys (in most of the animal trials of vaginal anti-HIV microbicides, the monkeys are given injectables in order to increase the risk of transmission). However, no physiological studies of humans have shown evidence of a similar effect. The increase of transmisability in both directions suggests that there may be a physiological change after all.


  1. Hormonal contraceptives and HIV transmission – do we *want* to separate biology from behavior? | MethodLogical

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