VANCOUVER, British Columbia The proportion of infants who acquire HIV infection from their mothers has declined substantially in the United States after the August 1994 publication of guidelines that recommended using zidovudine (ZDV) to prevent mother-to-child transmission, researchers reported here recently at the 11th International Conference on AIDS.
In a prospective study of children born to women with HIV infection, R. J. Simonds, MD, and colleagues at the Centers for Disease Control and Prevention found that of 1,019 children born prior to Sept. 1, 1994, 217 (21%) were infected with the virus, compared with 18 (11%) of 164 children after that date.
The prevalence of ZDV use in mothers prenatally or in newborns, or both, increased from 17% among women who delivered before Sept. 1, 1994 to 80% among those delivering later, the investigators reported.
The decline in transmission rate also may be due to a lower prevalence of other risk factors for transmission, such as giving birth four or more hours after rupture of fetal membranes, according to Simonds and colleagues. Prior to Sept. 1, 1994, 55% of women gave birth four or more hours after rupture of fetal membranes, compared with 37% of women who gave birth after Sept. 1, 1994.
Recommendations to use ZDV to prevent mother-to-child transmission were based largely on the findings of the landmark AIDS Clinical Trials Group 076 study, which looked at pregnant women infected with HIV. Women who took ZDV had a two-thirds lower risk of transmitting HIV to their infants than women who did not.
A mother's risk for transmitting HIV to her child is related to the amount of circulating HIV particles, as measured by the number of HIV RNA copies detected per milliliter of plasma, according to study data presented at the conference.
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