Direct Pregnancy-Related Death Classification
Direct pregnancy-related death is defined as death resulting from obstetric complications of pregnancy itself, interventions, omissions, incorrect treatment, or a chain of events resulting from any of these factors—as opposed to deaths from pre-existing conditions or incidental causes. 1
Core Definition and Timeframe
Pregnancy-related death encompasses deaths occurring during pregnancy or within 1 year of the end of pregnancy from a cause related to pregnancy or its management, according to the CDC's Pregnancy Mortality Surveillance System. 1 However, the standard WHO definition and maternal mortality ratio calculations typically use a 42-day postpartum threshold. 2, 3
Classification Categories
Direct pregnancy-related deaths are distinguished from two other categories:
Direct obstetric deaths: Result from obstetric complications of pregnancy, labor, and the postpartum period, including complications from interventions, omissions, incorrect treatment, or chain of events from these factors 1
Indirect obstetric deaths: Result from pre-existing disease or disease that developed during pregnancy that was aggravated by the physiologic effects of pregnancy 1
Accidental or incidental deaths: Deaths from unrelated causes that happen to occur during pregnancy or the postpartum period 2, 4
Leading Direct Causes in the United States
According to CDC surveillance data from 2007-2016, the leading causes of pregnancy-related death include:
- Cardiovascular conditions (most common) 1
- Infection/sepsis 1
- Hemorrhage 1
- Hypertensive disorders (preeclampsia/eclampsia) 1
- Thromboembolism (leading cause of direct maternal death in some high-income countries) 1
- Amniotic fluid embolism 1, 2
Critical Timing Considerations
More than half of all pregnancy-related deaths occur after birth, with nearly 12% occurring 43 to 365 days postpartum. 1 This extended risk period is often missed by standard 42-day surveillance definitions, potentially underestimating true maternal mortality by excluding late deaths that remain pregnancy-related. 5
Common Pitfalls in Classification
The addition of the pregnancy checkbox to U.S. death certificates in 2003 has resulted in both improved detection and misclassification/overreporting of maternal deaths. 1 Many pregnancy-associated deaths are not easily identified as such when pregnancy status is not listed on death certificates, leading to significant underreporting—vital statistics systems can miss up to 90% of actual maternal mortality events. 6
Two-thirds of pregnancy-related deaths are preventable, with both patient-level and health system factors contributing to these deaths. 1, 7