Perinatal HIV transmission
Perinatal HIV transmission - 1
Risk factors for mother-to-baby transmission of HIV-1 infection were worked out before zidovudine treatment of mother and child became routine. Now US data have been used to assess risk factors in women treated with zidovudine.
The trial included 480 pregnant women with advanced HIV-1 infection who were treated with zidovudine and also randomised to either HIV-1 hyperimmune globulin or non-specific immunoglobulin infusions. (Since the allocation did not significantly affect HIV-1 transmission, the randomisation was ignored for the purposes of this analysis.) The rate of perinatal transmission was related to maternal levels of HIV-1 RNA at baseline and at delivery. Eighty-four women had undetectable HIV-1 at baseline and 107 at delivery, and none of these transmitted the infection to their baby. The odds ratio for transmission was 2.4 per log increase in number of copies of HIV-1 RNA at baseline and 3.4 per log increase at delivery.
Maternal HIV-1 RNA level is the best predictor of perinatal transmission in women treated with zidovudine. At levels less than 500 copies/mL transmission is very unlikely.
Perinatal HIV-1 transmission - 2
Another US trial has provided more data about HIV-1 RNA levels and perinatal transmission.
This trial included 552 women with HIV-1 infection and a singleton pregnancy of whom 230 received antenatal zidovu-dine therapy. The overall rate of perinatal transmission was 24% before March 1994 (when the results of the major trial of zidovudine prophylaxis were made available) and 9% after that date. Rate of transmission increased with maternal HIV-1 RNA levels: level <1000 copies/mL, rate 0%; 1000-10 000, 17%; 10 000-50 000, 21%; 50 000-100 000, 31%; >100 000, 41%. In women with >100 000 copies/mL not treated with zidovudine, transmission was 63% (19/30). The level of HIV-1 RNA did not affect the timing of infection in the infants.
Maternal HIV-1 RNA level affects the risk of perinatal transmission but not its timing.
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