New ACTG 076 Analysis Emphasized Importance of Offering AZT Therapy to All HIV-Infected Pregnant Women

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"Even when antiretroviral drugs with a greater impact on reducing viral load are indicated for the
health of a pregnant HIV-infected women, she and her physician should strongly consider
incorporating AZT into her treatment regimen, and should continue AZT during delivery and to
the newborn, according to the ACTG 076 protocol."
"Further research is needed into the mechanisms whereby AZT reduces perinatal HIV
transmission, as well as into the risk factors for transmission at all levels of maternal viral load,"
she adds.
A related editorial by Catherine M. Wilfert, M.D., of Duke University Medical Center
appears in the same issue. Dr. Sperling and Dr. Wilfert are investigators within the Pediatric
AIDS Clinical Trials Group, a nationwide network of clinical trials sites sponsored by NiAID and
the National Institute of Child Health and Human Development (NICHD).
The current article is the second publication from a randomized, double-blind clinical trial
known as ACTG 076. The study enrolled 477 pregnant, HIV-infected women between April
1991 and December 1993, and assessed the safety and efficacy of AZT in reducing the risk of
maternal-infant transmission. Women enrolled in the study had CD4+ T cell counts greater
than 200 cells/mm3 of blood at study entry. They received AZT beginning in the second or third
trimester of pregnancy and during labor and delivery; their newborns received the drug for the
first six weeks of life.
The first publication from ACTG 076 analyzed data from 363 mother-infant pairs in
which at least one culture of the infant's blood had been performed, and demonstrated that the
AZT regimen reduced mother-to-infant transmission by approximately two-thirds, with minimal
short-term toxic effects (see The New England Journal of Medicine, 11/03/94).
The current analysis of ACTG 076 data included 402 mother-infant pairs in which the
HIV infection status of the infant was definitively known at 18 months of age. Among the
mother-infant pairs, 198 had been assigned to receive AZT during the study and 204 had been
assigned to the placebo group. Fifteen infants in the AZT group (7.6 percent) were HIVinfected; in the placebo group, 46 infants (22.6 percent) were HIV-infected.
The investigators tested stored samples of maternal blood collected when women
entered the study and when they delivered their infants. For their analyses, the researchers
used two sensitive assays not available at the start of ACTG 076, the branched DNA assay and
a reverse transcription PCR assay. Each of these assays is used to measure levels of HIV's

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