This is a retrospective comparison of pregnant women with perinatally acquired HIV-infection (PAH) with a cohort of pregnant women with behaviorally acquired HIV-infection (BAH). PAH cases (11 women) included all pregnant adolescents followed at our HIV clinic from January 2000 to January 2009. BAH cases (27 women) were randomly selected from all deliveries within the study period at the same institution. Demographics, mode of delivery, CD4+ counts, and viral loads (VLs) before, during, and six months postpartum, as well as neonatal outcomes, were reviewed.CD4 counts were significantly lower in the PAH group. VLs were statistically higher in the PAH group. VLs were undetectable at delivery in 60% of the PAH group compared with 88% of the BAH group. No cases of vertical transmission occurred.PAH women may be at a higher risk for HIV-related disease progression. This may increase vertical transmission risks. Further studies and interventions with this growing population are warranted.