Background: Anesthesia-related complications are the sixth leading cause of pregnancy-related death in the United States. This study reports characteristics of anesthesia-related deaths during obstetric delivery in the United States from 1979-1990.

Methods: Each state reports deaths that occur within 1 yr of delivery to the Centers for Disease Control and Prevention as part of the ongoing Pregnancy Mortality Surveillance. Maternal death certificates (with identifiers removed) matched with live birth or fetal death certificates when available from 1979-1990 were reviewed to identify deaths due to anesthesia, the cause of death, the procedure for delivery, and the type of anesthesia provided. Maternal mortality rates per million live births were calculated. Case fatality rates and risk ratios were computed to compare general to regional anesthesia for cesarean section deliveries.

Results: The anesthesia-related maternal mortality rate decreased from 4.3 per million live births in the first triennium (1979-1981) to 1.7 per million in the last (1988-1990). The number of deaths involving general anesthesia have remained stable, but the number of regional anesthesia-related deaths have decreased since 1984. The case-fatality risk ratio for general anesthesia was 2.3 (95% confidence interval [CI], 1.9-2.9) times that for regional anesthesia before 1985, increasing to 16.7 (95% CI, 12.9-21.8) times that after 1985.

Conclusions: Most maternal deaths due to complications of anesthesia occurred during general anesthesia for cesarean section. Regional anesthesia is not without risk, primarily because of the toxicity of local anesthetics and excessively high regional blocks. The incidence of these deaths is decreasing, however, and deaths due to general anesthesia remain stable in number and hence account for an increased proportion of total deaths. Heightened awareness of the toxicity of local anesthetics and related improvements in technique may have contributed to a reduction in complications of regional anesthesia.