Value and disvalue of the pregnancy checkbox on death certificates in the United States–impact on newly released 2018 maternal mortality data

Maternal mortality is a sentinel health indicator. To improve the identification of maternal deaths, a pregnancy question was added during the 2003 revision of the US standard death certificate. Its adoption across all states in the United States took 16 years (2003–2018), and therefore the National Center for Health Statistics did not provide the national maternal mortality rate between 2007 and 2018. During this time, researchers raised questions about the accuracy of the checkbox information, particularly regarding its contribution to overreporting of maternal deaths in the United States. Checkbox errors were especially evident for women aged >40 years and for nonspecific causes of death. In January 2020, the NCHS resumed the reporting of maternal mortality data and provided the 2018 figures using a new coding method (ie, the 2018 method). Despite internal analyses suggesting the presence of both high false positive and high false negative pregnancy checkbox errors, the National Center for Health Statistics reported identification of 658 maternal deaths nationwide and a maternal mortality rate of 17.4 deaths per 100,000 live births for 2018. The 2018 coding method restricts the entry of checkbox information to decedents aged 10–44 years; the information cannot, therefore, be entered for women aged >45 years when no pregnancy-related cause of death information is indicated on the death certificate. Reported deaths with a pregnancy or obstetrical condition entered in the cause of death section of the death certificate continue to be coded as maternal deaths regardless of age. The 2018 method likely corrects errors introduced by the use of the checkbox for women aged >45 years, but whether it provides accurate maternal mortality figures remains unknown. We call for efforts to urgently and systematically validate the pregnancy checkbox information. Post hoc coding adjustments cannot substitute for providing accurate and actionable maternal mortality data.