These results include one unconfirmed in utero infection in the NRTI group, in an infant who died without a confirmed AIDS-defining cause after a positive PCR result at birth. The study was not powered to compare rates of mother-to-child transmission according to randomized group, and no significant betweengroup differences were detected: 6 of 283 liveborn infants in the NRTI group (2.1%) were infected, as compared with 1 of 270 live-born infants in the protease-inhibitor group (0.4%) (percentage-point difference, 1.7; 95% CI, −2.0 to 7.1). The timing and characteristics of transmission are included