A new analysis of data from a clinical trial conducted by the HIV Prevention Trials Network (HPTN) casts doubt on at least one study suggesting that women using hormonal contraception are at greater risk of acquiring HIV, according to a presentation by researchers at the International Microbicide Conference held April 15–18 in Sydney.

The finding that neither injectable nor oral hormonal contraceptives are themselves associated with an increased risk of acquiring HIV comes from a retrospective review of data from HPTN 035, a Phase II HIV prevention trial that evaluated the vaginal microbicides PRO 2000 and BufferGel. However, coupled with a diagnosis of either gonorrhea or Chlamydia, hormonal contraceptive use was associated with statistically significant greater risk of HIV infection in the analysis involving roughly 3,000 African women enrolled in the study between 2005 and 2008.

The analysis comes on the heels of the World Health Organization (WHO) announcing it will maintain its current guidance on the use of hormonal contraceptives, which do not restrict their use by women living with HIV or at high risk of HIV. The WHO said that although some studies—including one initially presented at the 6th IAS Conference on HIV Pathogenesis, Treatment and Prevention last summer in Rome—have suggested a possible increased risk of HIV acquisition with the use of progesterone-only injectable contraception, the totality of data is inconclusive.

Originally presented at a conference in 2009, HPTN 035 found that PRO 2000 was 30 percent more effective than a placebo in preventing HIV, although this finding was not statistically significant. BufferGel had no protective effect against HIV in the study.