Prevention of mother-to-child transmission of human immunodeficiency virus (HIV) with antiretroviral therapy (ART) has been highly successful. However, HIV-exposed uninfected (HIV-EU) infants might be at increased risk for low birth weight and/or preterm birth. We compared the birth weights and gestational ages of HIV-EU infants to those of HIV-unexposed control infants in Bronx, New York, an epicenter of the HIV epidemic in the United States. This study was performed with a retrospective cohort of HIV-EU infants born at Montefiore Medical Center between 2008 and 2012 and HIV-unexposed control infants. Each HIV-EU infant was matched according to year of birth with 5 HIV-unexposed controls from the New York City Department of Health and Mental Hygiene birth certificate database. We used regression models to assess the association between HIV exposure and birth weight while controlling for potential confounders. A secondary analysis was performed to determine the association of maternal protease inhibitor-based ART use and birth weight among HIV-EU infants. We included 155 HIV-EU infants born between 2008 and 2012 (51% female, 61% black, 32% Hispanic) and 775 HIV-unexposed infants. The mean (± standard deviation) unadjusted birth weights were 2971 ± 616 g (HIV-EU infants) and 3163 ± 644 g (HIV-unexposed infants) (P < .01). Multivariable regression revealed significantly lower birth weight for the HIV-EU infants (difference, -101.5 g [95% confidence interval, -181.4 to -21.6]). We found no difference in mean birth weight or gestational age with maternal protease inhibitor-based ART use when compared to the use of other regimens. We found significantly lower birth weight among HIV-EU infants. Long-term prospective studies are necessary to determine the implications of this finding on infant growth and development.