Elective caesarean-section versus vaginal delivery in prevention of vertical HIV-1 transmission: a randomised clinical trial

Background Results from observational studies suggest that caesarean-section delivery may reduce the risk of mother-to-child transmission of HIV-1 infection in comparison with vaginal delivery. We carried out a randomised clinical trial to address this issue and to assess the extent of postdelivery complications. Methods Eligible women were between 34 and 36 weeks of pregnancy, with a confirmed diagnosis of HIV-1 infection, and without an indication for caesarean-section delivery or a contraindication to this mode of delivery. Women were randomly assigned elective caesarean-section delivery at 38 weeks of pregnancy or vaginal delivery. An infant was classified as uninfected if he or she became negative for antibody to HIV-1 by age 18 months or was negative for virus by PCR or culture on at least two occasions, with no clinical, immunological, or viral evidence of infection. From 1993, to March, 1998, 436 women were randomised. Findings We present the results of an analysis updated to November, 1998, with data on the infection status of 370 infants. Three (1·8%) of 170 infants born to women assigned caesarean-section delivery were infected, compared with 21 (10·5%) of 200 born to women assigned vaginal delivery (p<0·001). Seven (3·4%) of 203 infants of women who actually gave birth by caesarean section were infected compared with 15 (10·2%) of 167 born vaginally (p=0·009). There were few postpartum complications and no serious adverse events in either group. Interpretation Our findings provide evidence that elective caesarean-section delivery significantly lowers the risk of mother-to-child transmission of HIV-1 infection without a significantly increased risk of complications for the mother.