A new study has linked the use of Depo-Provera (medroxyprogesterone acetate), an injectable type of birth control, to an increased risk of HIV infection. The study was conducted by researchers at the University of California at Berkeley and published in The Lancet last Thursday.
There are roughly 41 million women in the world who use injectable forms of birth control out of the 144 million who use hormonal contraception in general.
Researchers conducted a large meta-analysis of 12 studies in sub-Saharan Africa, which were selected on the strictness of their methodology; this includes, for instance, whether they accounted for the use of condoms. Data from 39,500 women were included. Other forms of contraceptives analyzed in the studies included the injectable norethisterone oenanthate (sold as NET-EN), combined oral contraceptives and progestin-only pills. The increased risk of HIV infection was only observed with Depo-Provera.
There was a moderate 40 percent increased risk of HIV infection in women who used Depo-Provera compared to women using non-hormonal methods and those who did not practice birth control. In studies analyzing women in the general population, the risk was slightly lower at 31 percent.
Lead author Lauren Ralph, who did the study for her Rh.D dissertation in epidemiology, said “We embarked on this study because of the inconsistency in the scientific literature on this topic,” according to the UC Berkeley Newscenter website. “The results have potentially broad implications because hormonal contraceptives remain popular for women worldwide.”
The authors said it was unclear why there was an increased risk with Depo-Provera compared with other types of hormonal contraception. One potential explanation could be that it changes the vaginal lining or environment due to higher levels of progestin, the synthetic form of the natural hormone progesterone. The study did not look at physiologic effects of the contraceptives.