Objective: To use data from the Centers for Disease Control and Prevention's (CDC) Pregnancy-Related Mortality Surveillance System to examine trends in pregnancy-related mortality and risk factors for pregnancy-related death.
Methods: In collaboration with ACOG and state health departments, the Pregnancy-Related Mortality Surveillance System has collected information on all deaths caused by pregnancy since 1979. Multiple data sources were used, including national death files, state health departments, maternal mortality review committees, individuals, and the media. As part of the initiation of the Pregnancy-Related Mortality Surveillance System in 1987, CDC staff contacted state health department personnel and encouraged them to identify and report pregnancy-related deaths. Data were reviewed and coded by experienced clinicians. Pregnancy-related mortality ratios (pregnancy-related deaths per 100,000 live births) were calculated.
Results: After decreasing annually after 1979, the reported pregnancy-related mortality ratio increased from 7.2 in 1987 to 10.0 in 1990. This increase occurred among women of all races. A higher risk of pregnancy-related death was found with increasing maternal age, increasing live-birth order, no prenatal care, and among unmarried women. The leading causes of pregnancy-related death were hemorrhage, embolism, and hypertensive disorders of pregnancy. During the periods 1979-1986 and 1987-1990, the cause-specific pregnancy-related mortality ratios decreased for deaths due to hemorrhage and anesthesia, whereas pregnancy-related mortality ratios due to cardiomyopathy and infection increased. The leading causes of death varied according to the outcome of the pregnancy.
Conclusion: Increased efforts to identify pregnancy-related deaths have contributed to an increase in the reported pregnancy-related mortality ratio. More than half of such deaths, however, are probably still unreported. Adequate surveillance of pregnancy-related mortality and morbidity is necessary for interpreting trends, identifying high-risk groups, and developing effective interventions.