OBJECTIVE To evaluate the possible association between protease inhibitor (PI) and premature birth and low birth-weight in HIV-infected pregnancies. METHODS Data were collected retrospectively for maternal and pregnancy characteristics, antiretroviral medication, lowest CD4 count and highest viral load during pregnancy, and pregnancy outcomes. χ(2) Analysis, Student's t-test, and multiple logistic regression analysis were performed. RESULTS Data from 161 HIV-infected women who delivered singleton gestation were analyzed. Fifty-three received an antepartum regimen with PI, 84 received a regimen without PI, and six did not receive antepartum treatment. The mean estimated gestational age (EGA)± SD at delivery was 37.7 ± 3.2 weeks. The premature birth rate was 18.4%. No difference was detected between women receiving the antiretroviral regimen including PI and those on the regimen without PI or on no antepartum medication with regard to: EGA ± SD at delivery (37.7 ± 3.2 vs. 37.6 ± 3.1 weeks, respectively, P=0.87), rate of premature birth (14% vs. 20.6%, respectively, P=0.32) and low birth-weight (12.5% vs. 20.2%, respectively, P=0.25). In multiple logistic regression analysis, PI was not associated with premature birth or low birth-weight. CONCLUSIONS Women receiving antiretroviral therapy with PI have a similar rate of premature birth and low birth-weight as women receiving antiretroviral therapy without PI or on no medication.