BACKGROUND Maternal Mortality Surveillance has been conducted by the State of Michigan since 1950, and anesthesia-related maternal deaths were most recently reviewed for the years 1972-1984. METHODS Records for pregnancy-associated deaths between 1985 and 2003 were reviewed to identify 25 cases associated with a perioperative arrest or major anesthetic complication. Four obstetric anesthesiologists independently classified these cases, and disagreements were resolved by discussion. Precise definitions of anesthesia-related and anesthesia-contributing maternal death were constructed. Anesthesia-related deaths were reviewed to identify the chain of medical errors or care management problems that contributed to each patient death. RESULTS Of 855 pregnancy-associated deaths, 8 were anesthesia-related and 7 were anesthesia-contributing. There were no deaths during induction of general anesthesia. Five resulted from hypoventilation or airway obstruction during emergence, extubation, or recovery. Lapses in either postoperative monitoring or anesthesiology supervision seemed to contribute to 5 of the 8 anesthesia-related deaths. Other characteristics common to these cases included obesity (n=6) and African-American race (n=6). CONCLUSIONS The 8 anesthesia-related and seven anesthesia-contributing maternal deaths in Michigan between 1985 and 2003 illustrate three key points. First, all anesthesia-related deaths from airway obstruction or hypoventilation took place during emergence and recovery, not during the induction of general anesthesia. Second, system errors played a role in the majority of cases. Of concern, lapses in postoperative monitoring and inadequate supervision by an anesthesiologist seemed to contribute to more than half of the deaths. Finally, this report confirms previous work that obesity and African-American race are important risk factors for anesthesia-related maternal mortality.