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SUNDAY, May 23 (HealthDay News) -- Men in a relationship with an HIV-positive woman face double the risk of becoming infected themselves when their partner is pregnant, new research reveals.
The finding is slated for presentation Sunday at the International Microbicides Conference in Pittsburgh.
The two-year study -- launched in Botswana, Kenya, Rwanda, South Africa, Tanzania, Uganda and Zambia -- focused on more than 3,300 couples in which one of the partners was HIV-positive.
Dr. Nelly Mugo, from the University of Nairobi and Kenyatta National Hospital in Nairobi, and colleagues teamed with investigators from the University of Washington in Seattle to track 1,085 couples in which the man was HIV-positive, and 2,236 couples in which the woman was infected.
During the duration of the study, 823 pregnancies occurred. The study authors found that pregnancy increased HIV transmission in both directions: male-to-female and female-to-male.
However, the observed infection risk for women appeared to be a function of several factors beyond pregnancy itself, including sexual behavior. For men, the link between pregnancy and risk increase was much stronger and more direct, Mugo's team noted.
Factors such as the viral load and CD4 count (an indicator of immune system strength) of the infected female partner had no impact on the man's risk. Nor did the man's circumcision status or whether or not the couple had engaged in unprotected sex, the researchers found.
The research team therefore theorized that the doubling of female-to-male transmission risk during pregnancy might be attributed to both immunological and physiological changes -- as yet unidentified -- that are triggered by pregnancy. But they cautioned that more research will be needed to explore this possible explanation.
For more on HIV prevention, visit the U.S. Centers for Disease Control and Prevention's National Prevention Information Network.