Recommendations of the U.S. Public Health Service Task Force on the Use of Zidovudine to Reduce Perinatal Transmission of Human Immuno deficiency Virus

Vol. 43 / No. RR-11

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Further clinical trials should be designed to assess the efficacy of interventions
that are initiated late in the third trimester for preventing perinatal transmission.
Recommendation:
The health-care provider should recommend the full ACTG Protocol 076 regimen in the context of a risk-benefit discussion with the pregnant woman. The
woman should be informed that ZDV therapy may be less effective than that
observed in ACTG Protocol 076, because the regimen is being initiated late in the
third trimester.
Ill. Pregnant HIV-infected women with CD4+ T-lymphocyte counts <200/ L who
are at 14-34 weeks of gestation, who have no other clinical indications for ZDV,
and who have no history of extensive (>6 months) prior antiretroviral therapy.
Discussion:
Women in this group meet the current standard of care for ZDV treatment of
HIV infection for their own benefit (30,3 1); therefore, administration of ZDV during pregnancy for these women provides direct benefit to them as well as
potential benefit to their infants. The risk for HIV transmission to the infants of
HIV-infected pregnant women with low CD4+ T-lymphocytes or percent of total
lymphocytes ranges from 22% to 60% (32-38).Viral load has been shown to
increase as CD4+ T-lymphocyte count decreases (39); thus, baseline viral loads
can be expected to be high among the women in this group.
Although viral replication and resultant capacity for mutations in this group
are high, preexisting ZDV-resistant viral strains are unlikely to be present
because these women have had little or no exposure to ZDV. Therefore, ZDV
therapy can be expected to result in an acute reduction in maternal viral load
analogous to that observed in women who have CD4+ T-lymphocyte counts
200/pL. Additionally, the mother's CD4+ T-lymphocyte count would not be
expected to affect ZDV levels or toxicity in the infant after administration of ZDV
during labor and the first 6 weeks of life. Hence, maternal CD4+ T-lymphocyte
count should not affect the potential utility of neonatal levels of systemic ZDV for
reducing intrapartum transmission.
Although this population of pregnant women was not studied in ACTG Protocol 076, addition of the intrapartum and neonatal components of the ACTG
Protocol 076 ZDV regimen to antenatal maternal therapy may reduce the risk for
HIV transmission. However, the magnitude of the effect of ZDV on reducing the
transmission rate in this group may not be the same as that demonstrated in
ACTG Protocol 076 for women with CD4+ T-lymphocyte counts 200. Further
clinical trials should assess the utility of interventions in this group of women.
Because ZDV therapy is clinically indicated for these women for their own
health, the additional risk of the remainder of the ACTG Protocol 076 regimen is
the discomfort to the woman of another intravenous infusion during labor and
the possible effects of the additional 6 weeks of ZDV exposure for the infant.
Recommendation:
The health-care provider should recommend initiation of antenatal ZDV therapy to the woman for her own health benefit (31 ). The intrapartum and neonatal