Two studies supported by the National Institutes of Health (NIH) provide compelling evidence that the amount of HIV in a pregnant woman's blood, known as the maternal HIV viral load, is the prime risk factor for transmitting the virus to her baby.
Women who had high levels of HIV in their blood -- whether they received the anti-HIV drug AZT or not -- transmitted the virus to their infants more often than women with low levels of HIV. The studies, which appear in the August 5 issue of The New England Journal of Medicine, underscore the importance of treatment strategies aimed at reducing viral load in HIV-infected pregnant women.
"Although we know that various factors can contribute to perinatal HIV transmission," says Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases (NIAID), which co-sponsored the studies, "these findings suggest that maternal viral load is the most important one."
The first report analyzed data from a clinical trial conducted by the Pediatric AIDS Clinical Trials Group. The second report comes from the Women and Infants Transmission Study.
"Despite the use of anti-HIV therapy during pregnancy, some infants continue to be infected," says Duane Alexander, M.D., director of the National Institute of Child Health and Human Development (NICHD), which also co-sponsored the studies. "These results suggest that reducing HIV viral levels in women during pregnancy may further reduce the risk of transmission of HIV to their infants."
"The studies also emphasize the importance of developing novel techniques for monitoring viral load in these women," adds National Heart, Lung and Blood Institute (NHLBI) Director Claude Lenfant, M.D.
THE PEDIATRIC AIDS CLINICAL TRIALS GROUP (PACTG) STUDY
In this report, researchers measured HIV levels in stored blood samples from
HIV-infected pregnant women enrolled in a clinical trial known as PACTG 185,
says the study's principal author,
Contact: John Bowersox
NIH/National Institute of Allergy and Infectious Diseases