The Washington Post asked every state and the District for any data it had collected since 1990 on traumatic deaths of pregnant and postpartum women. Methods for identifying cases varied widely from state to state, and few could be sure they knew of all or even most cases.
Half the states were able to provide more than eight years of data, mostly based on death record notations or by linking various state records, or both. Twelve other states provided more limited information. Nearly all data collected were given without names.
When it was possible and legally permissible, The Post pieced together the identities of victims and did further research and interviews to identify trends and patterns. The newspaper independently found cases through medical examiners, newspaper archives and interviews.