Using hormonal contraception does not appear to increase women’s overall risk of contracting the AIDS virus, according to a U.S. National Institutes of Health study published on Thursday.

The study, published on the Web site of the journal “AIDS,” followed thousands of women in Africa and Asia and compared their patterns of contraceptive use to their risk of infection with HIV, the virus that causes AIDS.

“Understanding whether hormonal contraceptive use alters the risk of HIV acquisition among women is a critical public health issue,” the study authors wrote.

Some 6,000 women, in Uganda, Zimbabwe and Thailand enrolled in the study were offered a choice of the most commonly prescribed forms of hormonal contraception, birth control pills or DMPA (depot-medroxyprogesterone acetate) injections, as well as condoms.

Before enrolling, the women, ages 18 to 35, were either using no hormonal contraceptives or had used them for at least three months before the study began. None were infected with HIV when they enrolled, the researchers wrote.

The participants primarily were women who sought family planning services at clinics. They were tested for HIV four to five times a year for 15 to 24 months.

By the time the study ended, 213 African women and 4 Thai women had tested positive for HIV. Because there were too few cases in Thailand for a valid statistical interpretation, those cases were excluded from the final analysis, they said.

When the 213 cases were considered together, researchers found no evidence that use of hormonal contraceptives increased a woman’s chances of becoming infected with HIV, the study concluded.

“In summary, this large, multi-site study found no overall increased risk of HIV acquisition associated with hormonal contraceptive uses,” the study authors wrote.

However, the authors noted that their study could not rule out an increase in risk for HIV infection among those already at higher than normal risks, such as sex workers.

Reuters Health