Background: Little is known about whether a woman's risk of transmitting HIV perinatally increases over time and whether the infection outcome of a previous child affects the risk of transmitting HIV to subsequent children.
Methods: We analyzed data from 114 prospectively followed women who gave birth to at least 2 children after becoming infected with HIV to determine the risk for perinatal HIV transmission to these sibling pairs.
Results: The median interval between sibling births was 19 months. HIV infection occurred in 19 (17%) older siblings and 20 (18%) younger siblings (P = 0.87). Two (11%) of the 19 children with infected older siblings were infected compared with 18 (19%) of the 95 children with uninfected older siblings (P = 0.86). The risk for transmission to younger siblings was not associated with the interval between deliveries of the two siblings.
Conclusions: These data do not demonstrate that an HIV-infected woman's risk of transmitting HIV perinatally increases with time, although the observed interpregnancy interval was relatively short. The risk for perinatal transmission does not appear to be affected by the infection outcome of previous children. These findings may be useful for counseling HIV-infected women about their risk of transmitting HIV perinatally.