It is well known that pregnant women are more likely than others to contract HIV during intercourse with an HIV-positive partner. Surprising new results, however, show that men are twice as likely to contract the virus when they have intercourse with a pregnant HIV-positive woman. The increased risk remains even after researchers accounted for behavioral and other factors that increase HIV risk, researchers reported Monday at a Pittsburgh conference on the use of microbicides to block HIV transmission.
Dr. Nelly Mugo of the University of Nairobi and Kenyatta National Hospital in Nairobi and her colleagues studied 3,321 couples in which only one partner was initially HIV-positive; in 1,085 of the couples, the male was infected, and in 2,236 it was the female. During the two years of the study, 831 pregnancies occurred. For the women, the researchers found that a variety of factors, including sexual behavior, contributed to the increased risk of contracting the virus during pregnancy, said Mugo, who is also on the faculty of the University of Washington. For the men, however, the link between pregnancy and risk was much clearer, even after considering whether they wore protection or had been circumcised.
The increased risk probably arises from physiological changes to the vagina during pregnancy and perhaps to immunological changes as well, Mugo speculated, but more research will be necessary to pin down the link.
-- Thomas H. Maugh II