OBJECTIVE To identify the reasons for admitting pregnant women to intensive care units (ICUs) in Buenos Aires, Argentina. METHODS The admission diagnoses of pregnant women hospitalized over 2 years at 4 ICUs were retrospectively studied. RESULTS During the studied period, 242 (3.9%) of the 6271 ICU patients were pregnant women, for an incidence of 8.1 per 1000 deliveries. The main reasons for admitting them at ICUs were hypertensive disorders, followed by postpartum hemorrhage and sepsis. More than a third (39.7%) was in a first pregnancy. The main nonobstetric reason for admission was pneumonia. The median pregnancy duration on admission was 36 weeks (range, 33-38 weeks) but it was less than 34 weeks for 66 (27.2%) of the women, 12.4% on whom required ventilation. Mortality was highest among those admitted for nonobstetric reasons (13.3% vs 0.5%; P<0.05). The median stay for obstetric or nonobstetric conditions was 2 versus 5 days (range, 2-3 days vs 2-8 days) (P<0.001). CONCLUSIONS Postpartum hemorrhage and hypertensive disorders were the most common reasons for admitting pregnant women to an ICU, followed by sepsis. Nonobstetric causes of admission were associated with higher morbidity and mortality rates.