Before the introduction of ART and obstetrical interventions to reduce MTCT about 1 in 4 infants born to a woman infected with HIV became infected. Among infected infants approximately 50% of transmission occurs around the time of labor or delivery, 20–25% occurs in-utero, and 25–35% occurs postnatally secondary to breastfeeding [28
]. In developed countries today, MTCT rate are estimated at less than 2% with the use of ART during pregnancy and in labor, with cesarean deliveries for viral loads >1,000 (copies/mL), 6 weeks of neonatal ART prophylaxis and avoidance of breastfeeding [4
]. Although ART has markedly decreased the risk of MTCT in the United States among adult females infected with HIV, little is known about their effect among pregnant perinatallyinfected females.
The risk of MTCT among perinatally HIV infected females appears to be comparable to the MTCT among nonperinatally HIV infected parturients. The Pediatric AIDS Clinical Trials (PACTG) protocol 219 has enrolled and followed HIV-infected and non-HIV-infected children at clinical centers across the United States since September 2000 to study the complications of pediatric HIV infection. A subanalysis including only perinatally infected adolescent girls aged 13 or older identified a cohort of 638 adolescent girls in which there were 32 pregnancies resulting in live births. One infant was HIV infected, 29 were uninfected, and 2 had unknown infection status, for a rate of MTCT of 3.3% (95% CI = 0.1, 18.6) [7
]. All adolescent girls received ART during pregnancy with 26 receiving combination therapy with at least 3 drugs including a protease inhibitor (PI); the case of perinatal transmission occurred in 1 of the 2 girls receiving a PI and a nonnucleoside reverse transcriptase inhibitor (NNRTI). In the cohort described by Williams et al., there was 1 case (10%) of perinatal HIV transmission however this was attributed to patient noncompliance [19
]. At the time of publication of the European study, one of the nine infants was confirmed uninfected, seven were presumed uninfected and the most recently born was still indeterminate [17
]. Although this corresponds to a 0% MTCT the 95% confidence interval is wide because of the small sample size and the upper limit is 36.7%. An earlier study from Puerto Rico identified eight cases of pregnancy in perinatally HIV-infected females. These resulted in six viable infants with no MTCT at the time of publication [11
]. Most recently Millery et al. reported on 19 live births in a cohort of perinatally infected women from New York City in which there were no cases of MTCT [20
]. Young people may have problems adhering to ART and pregnancy could compound this [30
]. Therefore, young infected pregnant women need additional counseling about proper ART use and social support to achieve maximal viral suppression which is vitally important to preventing MTCT.