Objective: The recommendation to perform a perimortem cesarean delivery within 4 minutes of maternal cardiac arrest was introduced in 1986. This recommendation was based on the assumptions that cardiopulmonary resuscitation is ineffective in the third trimester because of aortocaval compression, and that fetal and perhaps maternal outcomes would be optimized by timely delivery. Our objective was to review the outcomes of perimortem cesarean deliveries to attempt to validate those assumptions. Study design: Ovid MEDLINE searches using maternal mortality, cardiopulmonary resuscitation, perimortem cesarean delivery, heart attack, and cardiac arrest from 1985 until 2004. Citations from bibliographies of identified publications were perused and cross-referenced for other potential articles. Case reports were included for analysis when mothers had complete cardiopulmonary arrest, and cardiopulmonary resuscitation had been initiated before cesarean delivery. Results: There were 38 cases of perimortem cesarean delivery identified; 34 infants survived (3 sets of twins, 1 set of triplets); 4 other infants survived initially, but died several days after the deliveries from complications of prematurity and anoxia. Of the 34 infants (25- 42 weeks’ gestation), time of delivery after maternal cardiac arrest was available for 25. Eleven infants were delivered within 5 minutes, 4 were delivered from 6 to 10 minutes, 2 were delivered from 11 to 15 minutes, and 7 were delivered more than 15 minutes. Of 20 perimortem cesarean deliveries with potentially resuscitatable causes, 13 mothers were resuscitated and discharged from the hospital in good condition. One other mother was successfully resuscitated after the delivery, but died within 24 hours from complications related to her amniotic fluid embolism. In 12 of 18 reports that documented hemodynamic status, cesarean delivery preceded return of maternal pulse and blood pressure, often in a dramatic fashion. Eight other cases noted improvement in maternal status. Importantly, in no case was there deterioration of the maternal condition with the cesarean delivery. We wish to emphasize the large selection bias in this data. Conclusion: Published reports from 20 years support, but fall far from proving, that perimortem cesarean delivery within 4 minutes of maternal cardiac arrest improves maternal and neonatal outcomes. Objective: The recommendation to perform a perimortem cesarean delivery within 4 minutes of the maternal cardiac arrest was introduced in 1986. This recommendation was based on the assumptions that cardiopulmonary resuscitation is ineffective in the third trimester because of aortocaval compression, and that fetal and perhaps maternal outcomes Our objective was to review the results of perimortem cesarean deliveries to attempt to validate those assumptions. Study design: Ovid MEDLINE searches using maternal mortality, cardiopulmonary resuscitation, perimortem cesarean delivery, heart attack, and cardiac arrest from 1985 until 2004. Citations from bibliographies of identified publications were perused and cross-referenced for other potential articles. Case reports were included for analysis when mothers had complete cardiopulmonary arrest, and cardiopulmonary resuscitation had been initiated before cesarean delivery. Results: There were 38 cases of pe 34 infants survived (3 sets of twins, 1 set of triplets); 4 other infants survived initially, but died several days after the deliveries from complications of prematurity and anoxia. Of the 34 infants (25-42 weeks’ gestation), time of delivery after maternal cardiac arrest was available for 25. 5 minutes, 4 were delivered from 6 to 10 minutes, 2 were delivered from 11 to 15 minutes, and 7 were delivered more than 15 minutes. Of 20 perimortem cesarean deliveries with potentially resuscitatable causes, 13 mothers were resuscitated and discharged from the hospital in good condition. One other mother was successfully resuscitated after the delivery, but died within 24 hours from complications related to her amniotic fluid embolism. In 12 of 18 reports that documented hemodynamic status, cesarean delivery preceded return of maternal pulse and blood pressure, often in a dramatic fashion. Eight other cases noted imprimportantly, in no case was there deterioration of the maternal condition with the cesarean delivery. We wish to emphasize the large selection bias in this data. Conclusion: Published reports from 20 years support, but fall far from proving, that perimortem cesarean delivery within 4 minutes of maternal cardiac arrest improves maternal and neonatal outcomes.