FIG. 1.

Proportion of children exposed to in utero antiretroviral (ARV) regimens by year of birth. Because the mother's regimen may have changed during pregnancy, a single maternal regimen was chosen as the most intense regimen among all regimens received at least 3 days. Regimen intensity was assigned to a hierarchy (least to most intensive): no ARVs, ZDV only, two NRTIs, other ARV regimens, three or more NRTIs, and HAART-equivalent combination ARVs (regimens consisting of three or more NRTIs or three ARVs from two or more classes). ZDV, zidovudine; NRTI, nucleoside reverse transcriptase inhibitor; HAART, highly active antiretroviral therapy.