Jared Baeten, associate professor in global health at the University of Washington's School of Public Health in Seattle, said the study involved studies of almost 3,800 heterosexual couples in the African countries of Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia.
One of the spouses had human immunodeficiency virus and one did not, some used hormone-based contraceptives, and some did not, Beaten said.
"We found the women who were HIV negative and used hormonal contraceptives had double the risk of HIV infection, compared to those who did not use a hormonal contraceptive," Baeten told United Press International.
"Over the past 15 years, public health studies that have pointed at biologic reasons -- the hormones used in the contraceptives -- for why contraceptive may heighten HIV risk, but the real reasons are not fully known."
For this study, most of the women were using an injectable contraceptive not the pill -- injectable contraceptives are the most common method in Africa because they are delivered in a single shot ever three months, Baeten said.
"Contraceptive choice and their use are important to women's health worldwide and these study results deserve further study and discussion before any woman reconsiders her contraceptive method."
The findings were presented at a conference of the International AIDS Society in Rome.
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