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

MMWR

August 5, 1994

these infected infants are being evaluated but have not yet been identified. Several case reports also have described perinatal transmission despite the
initiation of ZDV therapy during pregnancy (24-27).
Although long-term toxicity to infants is unknown, this risk must be weighed
against the decreased risk for transmission of an infection associated with substantial risk of death. Currently, there is no way to predict if an individual
pregnancy will be associated with HIV transmission; therefore, each fetus must
be considered to have an estimated 25% risk of a life-threatening infection. Because ZDV therapy reduced the rate of transmission by two-thirds (from 25.5%
to 8.3%), any long-term toxicity related to ZDV would have to be severe (e.g.,
malignancy or profound developmental delay) and relatively common among
ZDV-exposed infants to outweigh the substantial benefit.
Recommendation:
The health-care provider should recommend the full ACTG Protocol 076 regimen to all HIV-infected pregnant women in this category. This recommendation
should be presented to the pregnant woman in the context of a risk-benefit discussion: a reduced risk of transmission can be expected, but the long-term
adverse consequences of the regimen are not known. The decision about this
regimen should be made by the woman after discussion with her health-care
provider.
Clinical Situations Not Meeting the Study Entry Criteria
Information about the benefit and short-term risks of ZDV therapy is applicable from this trial only for women who meet the entry criteria of the study.
Recommendations about use of the ZDV regimen for women whose clinical conditions differ from the ACTG Protocol 076 eligibility criteria were derived from
consensus interpretation of available scientific data.
II. Pregnant HIV-infected women who are at >34 weeks of gestation, who have no
history of extensive (>6 months) prior antiretroviral therapy, and who do not
require ZDV for their own health.
Discussion:
This patient population has clinical characteristics similar to those of women
enrolled in ACTG Protocol 076; the major difference is gestational age at which
ZDV therapy would begin. Therefore, the ZDV regimen for these women would
differ from the ACTG Protocol 076 regimen only in duration of antenatal therapy.
As much as 50%-70% of perinatal transmission may occur close to or during
delivery (28). Therefore, the ACTG Protocol 076 ZDV regimen may have some
benefit when initiated at >34 weeks of gestation, although the intervention is
likely to decrease in effectiveness as the duration of antenatal ZDV administration is reduced. A study evaluating the effect of ZDV on quantitative p24 antigen
levels indicates that maximal effect is observed after 8-16 weeks of therapy (29).
A shorter duration of ZDV therapy may thus be associated with an effect on maternal viral load that is less than can be anticipated when ZDV is initiated before
34 weeks of gestation. Both potential risks and benefits for the woman and her
infant may decrease the closer to delivery that the ZDV regimen is initiated.