Objective: To determine the clinical course and perinatal outcomes of women with pneumonia complicating pregnancy.Methods: Between 1989 and 1993, we admitted 71 pregnant women for treatment of community-acquired pneumonia. Exposure and outcome variables as well as characteristics of their clinical course were identified and analyzed. Two-sample Wilcoxon rank-sum and Fisher exact tests were used for statistical analyses.Results: Five women had adverse pregnancy outcomes related to pneumonia: two maternal-fetal deaths, one preterm delivery, one fetal death, and one early abortion. Compared with women whose pregnancies went to term, these five women had a significantly lower mean oxygen pressure on admission (68 versus 83 mmHg). Other risk factors for adverse outcome included diffuse radiologic pulmonary involvement and current smoking of more than ten cigarettes per day. Neither illicit drug use nor anemia were risk factors. Although 31 of these 71 women had underlying chronic diseases, these were not associated with negative outcomes.Conclusions: Despite prompt hospitalization and treatment, antepartum pneumonia is potentially serious, even in young, otherwise healthy women. Although underlying maternal disease appears to be related to the development of antepartum pneumonia, we did not confirm previous reports that suggested its relation to adverse pregnancy outcome.