Maternal Mortality in the United States: Changes in Coding, Publication, and Data Release, 2018

This report describes changes in how the National Center for Health Statistics (NCHS) will code, publish, and release maternal mortality data and presents official 2018 maternal mortality estimates using a new coding method. Due to the incremental implementation of the pregnancy status checkbox item on the 2003 revised U.S. Standard Certificate of Death, NCHS last published an official estimate of the U.S. maternal mortality rate in 2007. As of 2018, implementation of the revised certificate, including its pregnancy checkbox, is complete for all 50 states (noting that California implemented a different checkbox than that on the U.S. Standard Certificate of Death), allowing NCHS to resume the routine publication of maternal mortality statistics. However, an evaluation of data quality indicated some errors with the reporting of maternal deaths (deaths within 42 days of pregnancy) following adoption of the checkbox, including overreporting of maternal deaths among older women. Therefore, NCHS has adopted a new method (to be called the 2018 method) for coding maternal deaths to mitigate these probable errors. The 2018 method involves further restricting application of the pregnancy checkbox to decedents aged 10-44 years from the previous age group of 10-54. In addition, the 2018 method restricts assignment of maternal codes to the underlying cause alone when the checkbox is the only indication of pregnancy on the death certificate, and such coding would be applied only to decedents aged 10-44 based solely on the checkbox when no other pregnancy information is provided in the cause-of-death statement. Based on the new method, a total of 658 deaths were identified in 2018 as maternal deaths. The maternal mortality rate for 2018 was 17.4 deaths per 100,000 live births, and the rate for non-Hispanic black women (37.1) was 2.5 to 3.1 times the rates for non-Hispanic white (14.7) and Hispanic (11.8) women. Rates also increased with age. Maternal mortality rates calculated without using information obtained from the checkbox are also presented for 2002, 2015, 2016, 2017, and 2018 to provide comparisons over time using a comparable coding approach across all states.