To evaluate the impact of zidovudine
(ZDV) intervention on vertical transmission and HIV-related mortality in two groups of pregnant mothers and their respective infants.
A modified long course Paediatric AIDS Clinical Trial Group 076 protocol was used. None of the infants was breast-fed. Maternal CD4 T lymphocyte counts and viral loads were not monitored. Infants were followed for clinical progress, and serial serologic testing was performed to the age of 24 months, or until two successive HIV (enzyme-linked immunosorbent assay) tests were negative. In a historically case-controlled prospective study, the transmission rate in ZDV-untreated mother-infant pairs in which infants were born during 1991 through 1995 was compared with the transmission rate in ZDV-treated mother-infant pairs in which infants were born between 1996 and 2000.
In the 151 HIV-seropositive pregnant women and their 153 infants studied (2 pairs of twins), 93 mother-infant pairs were treated, and 59 were untreated (control group). Vertical transmission occurred in 5.5% [95% confidence interval (95% CI) 1.9 to 12.5] of the treated group of infants and in 27.1% (95% CI 16.7 to 40.5) of the untreated group. There was a 79.7% (95% CI 59.8 to 92.1%) relative reduction risk of transmission, which was statistically significant (z
=3.18, two tailed P
= 0.0001). Three infant deaths (3.7%) were recorded in the untreated group, and 1(1%) death was recorded in the treated group. In ZDV-untreated infants, deaths occurred at age <1 year, resulting from respiratory complications. One ZDV-treated infant died at 4 years of age with Pneumocystis carinii
Our study demonstrated a statistically significant reduction in the vertical transmission of HIV after intervention with ZDV therapy.