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| |  AZT And C-Section Appear To Nearly Eliminate Mother-To-Child HIV Transmission GENEVA, SWITZERLAND -- June 29, 1998 -- HIV-positive pregnant women may have the best chance of preventing disease transmission to their newborns by having an elective cesarean delivery and undergoing zidovudine (AZT) therapy while pregnant, according to an article in the July 1 issue of The Journal of the American Medical Association, a special theme issue on HIV/AIDS. Laurent Mandelbrot, M.D., of Hôpital Cochin-Port Royal in Paris, France, and colleagues studied 2,834 mother-infant pairs in France to determine if the mode of delivery had an impact on perinatal HIV-1 transmission while mothers were undergoing AZT therapy. The researchers found among 1,917 mothers who did not receive AZT (of whom 1877 had information on mode of delivery), 17.2 percent transmitted HIV-1 to their infants. The 902 mothers who underwent AZT therapy had varying results. The researchers discovered that 11.4 percent of these mothers undergoing emergent cesarean delivery (C-section performed because of obstetrical complications) transmitted HIV-1 to their babies. Among those giving birth vaginally, 6.6 percent of the mothers transmitted HIV-1 virus. Among those undergoing an elective C-section, only 0.8 percent transmitted HIV-1 to the child. An elective C-section is one that occurs before the onset of labour and with intact membranes. A multivariate analysis of the data showed that the risk of transmission remained five-fold lower following elective cesarean section than following a vaginal delivery or emergent cesarean. "In the presence of zidovudine prophylaxis, we observed only one child infected with HIV-1 in 133 delivered by elective cesarean," they write. "In a multivariate analysis, transmission risk remained five-fold lower following elective cesarean delivery than in vaginal or emergent cesarean delivery." In contrast, among those mothers not undergoing AZT therapy, the method of delivery made very little difference in HIV transmission. A child was considered infected at 18 months if HIV-1 antibodies persisted or in the case of death from HIV-related disease and considered uninfected if two HIV antibody tests were negative. For children aged three to 18 months, infection status was determined using a DNA-polymerase chain reaction test and/or an HIV virus culture. The child was considered infected when two different samples tested positive, and uninfected when two different samples tested negative, at least one of which was at or beyond three months AZT use increased sharply as of March 1994, when an official policy was issued following the results of the French-American AIDS Clinical Trials Group 076 trial. The proportion of women treated was 15 percent in 1993, reached 90 percent by mid-1994 and was stable thereafter, according to the researchers. Current research indicates transmission of the disease from the mother to the child occurs primarily late in the pregnancy and during labour and delivery. The researchers say several studies show an increased risk of transmission associated with rupture of membranes before the onset of labour or more than four hours before delivery. A few studies indicate risk is associated with maternal hemorrhage or with bacterial infection during the pregnancy. Conversely, the conditions of delivery-related events, such as the length of labour, use of instruments for delivery, or episiotomy, appear to have little relationship to transmission. The authors say the impact that the mode of delivery has on transmission has been a topic of controversy. More information on: AZT
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