Recommendations from the Meeting on Prevention of Mother-to-Infant Transmission of HIV by Use of Antiretrovirals

Eligible participants were HIV-infected pregnant women who had received no
antiretroviral treatment during the current pregnancy, had no clinical indications for maternal
antepartum ZDV therapy, and had baseline CD4+ lymphocyte counts greater than 200
cells/mm'. The ZDV regimen consisted of antepartum ZDV (100 mg orally 5 times daily)
initiated between 14 and 34 weeks of gestation and continued throughout the remainder of
pregnancy, followed by intrapartum intravenous ZDV (loading dose 2 mg/kg starting in
labour, followed by continuous infusion of 1 nfg/kg/hour until delivery), followed by oral
administration of ZDV (syrup 2 mg/kg every 6 hours for 6 weeks beginning 8 to 12 hours
after birth) to the infant. The primary study endpoint, HIV infection of the infant, was
defined by one positive HIV culture obtained from peripheral blood. Specimens for viral
culture were obtained from the infants at birth, 12, 24 and 78 weeks postpartum.
At the time of the interim analysis, 477 women had been enrolled. The median age
was 25 years (range 15 to 43), the median CD4+ lymphocyte count was 550 cells/mm' (range
200 to 1,818), and the median gestational age at entry was 26 weeks. The baseline
characteristics of the women were balanced between the two randomized groups. Based on
a Kaplan-Meier estimate at 18 months, the MTI transmission rate of HIV in the placebo group
was 25.5% whereas the rate in the ZDV group was 8.3%. This corresponded to a 67.5%
relative reduction in transmission risk. This risk reduction was highly statistically significant
(two-sided p=0.000056).
Reported maternal and infant adverse events were similar in the two randomized
groups with the one exception that haemoglobin levels were lower among infants in the ZDV
group. The study currently provides no information regarding any late effects of ZDV in
infants, including those who do not become infected with HIV.