A systematic review of the most recent epidemiological evidence on hormonal contraceptive methods and the risk of HIV acquisition suggests a reassuring lack of increased risk for users of oral contraceptive pills, the NET-EN injectable contraceptive and implants. However, new data on intramuscular depot medroxyprogesterone acetate (DMPA), an injectable contraceptive most commonly sold as Depo-Provera, heightens existing concerns about a possible increase in risk of HIV acquisition in women who use the method, according to an analysis by the Guttmacher Institute, the World Health Organization (WHO) and other partners. The review appears in an article, "Update on hormonal contraceptive methods and risk of HIV acquisition in women: a systematic review of epidemiological evidence, 2016," by Chelsea Polis et al., published today in the journal AIDS.

Some studies have suggested that use of DMPA may increase women’s risk of acquiring HIV, though other studies have not shown this association. Whether or not such a causal association exists is important to determine, particularly for women in Sub-Saharan Africa, where high HIV rates coincide with high use of the DMPA injectable. This review updates a previous systematic review of the epidemiological data on such an association and incorporates the most current evidence published between January 2014 and January 2016.

"This is a critical area of research, given that hormonal contraceptives are highly effective methods for preventing unintended pregnancy and its health risks," says Dr. Chelsea Polis, senior research scientist at the Guttmacher Institute and the review’s lead author. "Many places where HIV rates are high also have high levels of unmet need for contraception, unintended pregnancy and maternal mortality. It is essential that we understand whether use of any particular hormonal contraceptive method could elevate women’s risk of HIV acquisition."

This review, like the previous one, shows no increased risk of HIV acquisition for women using oral contraceptive pills. The limited data on levonorgestrel implants suggest no increase in users’ risk of HIV, and no data are currently available for etonogestrel implants. For the NET-EN injectable, limited data in the previous review suggested the possibility of an increased risk of HIV acquisition, but that association is no longer suggested in currently available data. There continues to be no data available on the relationship between women’s use of contraceptive patches, rings or hormonal IUDs and their risk of HIV acquisition.

The new evidence on DMPA heightens previous concerns about a potential causal association between DMPA use and HIV acquisition for women. However, since the evidence comes from observational studies, which are vulnerable to certain methodological biases, it remains unclear if the association is definitively causal.

"While the data on other hormonal contraceptives, including the NET-EN injectable, are reassuring, our review identified new and increasingly concerning evidence on DMPA," says Dr. Tsungai Chipato, professor of obstetrics and gynecology at University of Zimbabwe and a coauthor of the review. "Determining if these new findings warrant a reconsideration of global clinical guidelines for DMPA is an important next step for the World Health Organization."  

"While definitively inferring causality with observational studies is challenging, it is worth noting that the methodological quality of studies looking at the association of DMPA use with HIV acquisition in women has improved dramatically over time," adds Polis. "This underscores the need to consider next steps on this issue carefully, in terms of clinical guidelines and further research."

The researchers note that estimating the impact of reduced reliance upon DMPA on potential reductions in HIV acquisition—as well as any concomitant increases in unintended pregnancy and maternal mortality—might be useful in considering appropriate country-level responses. The net public health impact would be expected to differ across sociodemographic and epidemiological contexts, and would also depend on what alternative contraceptive options are available and acceptable to women.

"Update on hormonal contraceptive methods and risk of HIV acquisition in women: a systematic review of epidemiological evidence, 2016," by Chelsea Polis et al., is currently available online and will appear in a forthcoming issue of AIDS.

Note: After the publication of this news release, the article "Update on hormonal contraceptive methods and risk of HIV acquisition in women: a systematic review of epidemiological evidence, 2016" was renamed. The article’s new title in the published journal is "An updated systematic review of epidemiological evidence on hormonal contraceptive methods and HIV acquisition in women."