The effects of general and regional anesthesia on neonates after cesarean section have been studied mainly on elective cases. In this paper we studied infants delivered by elective and nonelective cesarean section at the Winnipeg Women's Hospital from 1975 to 1983 (n = 3940) to determine the effect of anesthetic technique on neonatal outcomes. A trained anesthesia nurse interviewed all parturients and reviewed their antepartum, labor and delivery, and anesthesia records. Assessments of neonatal outcomes were based on 1- and 5-minute Apgar scores, need for positive pressure oxygen by mask or intubation, and neonatal deaths (within 30 days). These outcomes were determined in three subgroups of neonates delivered by cesarean section: those delivered by elective section, those delivered by urgent cesarean section for dystocia or failure of labor to progress, and those delivered by section because of fetal distress. Overall, 12.5% of the infants had 1-minute Apgar scores of 4 or less, and 1.4% had 5-minute Apgar scores of 4 or less. Neonates born to mothers given general anesthesia had worse outcomes than those born to mothers given regional anesthesia. Among neonates delivered after elective section, general anesthesia was associated with a higher incidence of low Apgar scores at 1 minute. In neonates delivered by nonelective section, general anesthesia was associated with higher rates of low Apgar scores at 1 and 5 minutes as well as greater requirements for intubation and artificial ventilation. There were no differences seen in neonatal death rates with general and regional anesthesia in the three groups.(ABSTRACT TRUNCATED AT 250 WORDS)