Hormonal contraception use doesn't up HIV risk
Using hormonal contraception does not appear to increase women's overall risk of infection with the AIDS virus, according to results from a new study commissioned by the National Institute of Child Health and Human Development (NICHD).1
Understanding whether hormonal contraceptive use alters a woman's risk for HIV is a "critical public health issue," say the study's authors: More than 100 million women around the world use hormonal contraception, and 18 million women have been infected with HIV, most during heterosexual relations.2,3 To perform the study, researchers followed thousands of women in Africa and Asia and compared their patterns of contraceptive use to their risk of infection with HIV.
Do the findings provide a basis for changing current recommendations regarding contraceptive use? No, says Trent MacKay, MD, MPH, chief of the NICHD Contraception and Reproductive Health Branch. "The study findings do not alter the fact that, although hormonal contraception is effective for preventing pregnancy, it does not protect against HIV or other sexually transmitted infections," he says. "The only sure way to prevent sexual transmission of HIV is through abstinence; barring abstinence, using a latex condom, consistently and correctly, is highly effective against HIV infection."
Review the results
A total of 6,109 women participated in the study: 2,235 in Uganda, 2,296 in Zimbabwe, and 1,578 in Thailand. At the time of enrollment, the women were using no hormonal contraception, or had used oral contraceptives or depot medroxyprogesterone acetate (DMPA) for at least three months before the study began. Women who were not using hormonal contraception used such methods as condoms alone, diaphragms and spermicides, sterilization, withdrawal, or periodic abstinence, or used no birth control method.
In the study, the women were offered their choice of oral contraceptives or DMPA, as well as condoms. Researchers counseled women on how to use their chosen methods, as well as how to reduce their risk of HIV infection. Women also were examined for sexually transmitted infections and offered treatment if needed. HIV tests were administered four to five times a year for 15 to 24 months.
By the study's end, 213 African women had become infected with HIV, while only four Thai women were identified with the infection. Why the difference in infection rates? The Thai government policy of mandated condom use in brothels, implemented during the 1990s, may have affected the heterosexual spread of HIV, researchers surmise. Since there were too few Thai cases for a valid statistical interpretation, the researchers excluded them from the final analysis.
When the scientists analyzed all of the African HIV cases, they found no evidence that use of hormonal contraceptives increased a woman's chances of becoming infected with HIV. However, analysis findings indicated that the risk of HIV infection was two times greater for women with genital herpes (herpes simplex virus 2 or HSV-2) infection than it was for women without herpes infection at enrollment in the study, regardless of whether the women used hormonal contraception.
The researchers also noted differences in HIV infection risk among the subgroup of women not infected with genital herpes at enrollment, which comprised about half the women in the study. In this subgroup, women who used hormonal contraceptive methods had an increased HIV infection risk. Oral contraceptive users had almost three times and DMPA users had four times the risk of acquiring HIV when compared to women not using hormonal contraceptives. The authors state that "a solid biological explanation for our finding among the HSV-2-negative women is elusive."
What are the ongoing research needs when it comes to hormonal contraception and HIV acquisition?
"We need the results from other studies evaluating the modifying effect of HSV-2 infection on the hormonal contraception-HIV relationship," says Charles Morrison, PhD, senior epidemiologist in the Clinical Research Department at Family Health International, a Research Triangle Park, NC-based research organization. Morrison served as lead author of the research publication.
More studies also are needed to fully explore the potential modifying effect of age, observes Morrison. In particular, science needs to examine whether hormonal contraception, particularly DMPA, increases HIV acquisition risk among young women (15-24 years), he says. Other forms of hormonal contraception, such as contraceptive implants that contain different progestins from those found in DMPA, should be examined to see if they affect HIV acquisition risk differently, Morrison points out.
"Finally, we need to determine the risks and benefits of hormonal contraceptive use among HIV-infected women," he states. "In particular, we need to better understand whether or not HIV-infected, hormonal contraceptive users are more infectious to a sex partner, whether they are more likely to have rapidly progressive HIV infection, and whether they can safely use commonly prescribed antiretroviral therapies when compared to women not using hormonal contraception."
References
- Morrison CS, Richardson BA, Mmiro F, et al. Hormonal contraception and the risk of HIV acquisition. AIDS 2007; 21:85-95.
- Population Reference Bureau. Family Planning Worldwide 2002 Data Sheet. Washington, DC: Population Reference Bureau; 2002.
- UNAIDS. 2005 Report on the Global AIDS Epidemic, Executive Summary. Geneva: Joint United Nations Programme on HIV/AIDS (UNAIDS); 2005.
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