Timing Is Everything in Preventing HIV Spread From Mom to Baby
Oct. 4, 2000 -- HIV-infected pregnant women pass the virus on to their unborn babies less often if they begin treatment earlier in the course of pregnancy rather than later, researchers have found.
"The message is, 'Get tested early,'" says Kenneth McIntosh, MD, professor of pediatrics at Harvard Medical School and a co-author of the study. "There's a utility in taking AZT [a drug used to treat HIV] for a longer period of time." The study appears in the Oct. 5 issue of the New England Journal of Medicine.
The researchers also tried to determine the length of time that newborns should be given AZT to further prevent them from getting the virus. They found that babies born to HIV-infected mothers -- in cases where the mothers had taken a full course of AZT treatment -- were no more likely to develop HIV if they had taken AZT for three days than if they had taken them for six weeks.
That is an interesting finding and may change the way some physicians treat their newborn patients, says Edward Handelsman, MD, a lead researcher in pediatric HIV studies at the State University of New York Health Science Center in Brooklyn. "I would be much more comfortable giving the shorter dose to infants, or at least offering parents the option," especially if the baby isn't tolerating AZT very well, he tells WebMD.
In the study, Marc Lallemant, MD, of the Institute of Research and Development in Paris, and colleagues studied almost 1,500 pregnant women in Thailand, average age 25, who were infected with HIV. The researchers wanted to find out what the optimal length of AZT treatment was for both mothers and newborns to prevent transmission of HIV to the baby.
They divided the women into four groups -- all starting AZT at different points in their pregnancy with varying lengths of AZT treatment in their newborns as well.
The researchers found considerable differences among the three groups. The women who started AZT at the 28th week of pregnancy with their newborns taking the drug for three days did the best. Only 5% of these babies became infected with HIV.
The results suggest that when a woman receives the longer course of AZT during pregnancy, prolonged treatment of her baby may not have additional benefit, Catherine Peckham, MD and Marie-Louise Newell, MD, wrote in an editorial accompanying the study. On the other hand, if the mother has only been receiving AZT for a short time, longer treatment of the newborn might be helpful, they note.
This study might not be entirely relevant in the U.S. where most HIV patients receive a combination of drugs instead of just AZT, says Lynne Mofenson, MD, who is with the pediatric, adolescent, and maternal AIDS branch of the National Institute for Child Health and Human Development in Bethesda, Md.