Pregnancy may double the risk of female-to-male HIV transmission, according to research presented Sunday at the 2010 International Microbicides Conference in Pittsburgh.
Researchers with the University of Nairobi and University of Washington evaluated HIV transmission factors and pregnancy in a prospective study of 3,321 serodiscordant couples from seven African countries. Among the couples, which were followed for up to 24 months, 1,085 women were HIV-susceptible, or seronegative, and 2,236 men were HIV-susceptible. During the study, there were 823 pregnancies (320 HIV-negative women; 503 HIV-positive).
Among participants, 64 women acquired HIV-1 infection (incidence of 3.8 per 100 person-years). Of new female HIV cases, 17 (26.6 percent) occurred during pregnancy. Of the men, 57 acquired HIV during the study from their female partners, representing an incidence of 1.7 per 100 person-years. Among male HIV infections, 12 (21.1 percent) occurred during their partners' pregnancy.
Pregnancy was associated with a higher risk of male-to-female HIV transmission (hazard ratio [HR] 2.1, 95 percent confidence interval [CI] 1.2-3.7, p=0.009). However, the risk was attenuated to statistical insignificance after adjusting for female partner age, unprotected sex, and hormonal contraceptive use.
Pregnancy was also associated with an increased risk of female-to-male HIV transmission (HR 2.21, 95 percent CI 1.17-4.19, p=0.02). In contrast to the risk for females, the risk for males was not attenuated in adjusted analysis (adjusted HR 2.28, 95 percent CI 1.16-4.46, p=0.02). "Further adjustment for other factors, including plasma HIV-1 levels, CD4 count, and male circumcision, did not substantially change the findings," noted Dr. Nelly Mugo, of the University of Nairobi and Kenyatta National Hospital in Nairobi, and colleagues.
Increased female-to-male transmission of HIV during pregnancy might be due to pregnancy-related physiological and immunological changes that may increase the infectiousness of HIV-1, the researchers concluded. However, more research is necessary for confirmation.
To view the abstract presented at the conference, which concludes Tuesday, visit http://microbicides2010.org/files/pregnancy%20Mugo%20abstract.pdf.
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