A large study has clearly shown that a cesarean section, if performed soon enough, can drastically reduce the risk of transmitting the AIDS virus from a mother to her newborn. The findings, slated for publication in The New England Journal of Medicine in April, were disclosed today because of "their possible implications for public health," according to the journal. In the United States, HIV-positive pregnant women do not routinely undergo cesareans.
HIV transmission from mother to child occurs most often during labor and delivery, when the infant is exposed to body fluids in the mother's genital tract. European studies carried out in the early '90s suggested that so-called elective cesareans--performed before labor begins and the amniotic sac ruptures--could reduce that risk by more than half. Other researchers, however, mainly in the United States, failed to confirm that finding. But many of those teams didn't distinguish between elective and "regular" cesareans, carried out after the mother went into labor. The new study, led by pediatrician Jennifer Read of the National Institute of Child Health and Human Development in Bethesda, Maryland, is an analysis of data pooled from 15 European and American studies involving more than 8000 children.
Read and her colleagues found that elective cesareans cut the risk of infecting the newborn significantly when compared to vaginal delivery: from 7.3% to 2% in mothers who received the HIV-inhibiting drug AZT, and from 19% to 10.4% in mothers who didn't. There was almost no difference between transmission rates in nonelective cesareans and vaginal delivery, a finding that Read says may explain the discrepancy between the European and American trials. Even a cesarean done immediately after rupture of the membrane increases the risk, she says. "It's an important point not to miss the boat and do the cesarean real early," Read says.
"A lot of people have been waiting for these data," says Kevin Decock, an HIV specialist at the Centers for Disease Control and Prevention in Atlanta. "This is very persuasive evidence." But although the results may lead to a clear-cut strategy in the Western world, it won't be easy to come up with worldwide public health recommendations based on the study, says Decock. In less developed countries, the advantage of a cesarean has to be weighed against the increased risk of infections and other complications for the mother.