Vertical transmission of HIV in Rio de Janeiro, Brazil.

A cohort of 297 HIV-infected pregnant women was followed from January 1996 to December 2001. The overall transmission rate was 3.57% and remained constant over time. Low birth-weight was independently associated with a higher risk of vertical transmission (P=0.0072), whereas a longer duration of antiretroviral drugs during pregnancy was independently associated with a lower risk of transmission (P=0.0084). Further decreases in transmission should be obtained by initiating prophylaxis earlier in pregnancy.