OBJECTIVE: To analyze recent trends in maternal mortality by sociodemographic characteristics and cause of death and to evaluate data quality.
METHODS: This observational study compared data from 2008–2009 with 2013–2014 for 27 states and the District of Columbia that had comparable reporting of maternal mortality throughout the period. Maternal mortality rates were computed per 100,000 live births. Statistical significance of trends and differentials was evaluated using a two-proportion z-test.
RESULTS: The study population included 1,687 maternal deaths and 7,369,966 live births. The maternal mortality rate increased by 23% from 20.6 maternal deaths per 100,000 live births in 2008–2009 to 25.4 in 2013–2014. However, most of the increase was among women aged 40 years or older and for nonspecific causes of death. From 2008–2009 to 2013–2014, maternal mortality rates increased by 90% for women 40 years of age or older but did not increase significantly for women younger than 40 years. The maternal mortality rate for nonspecific causes of death increased by 48%; however, the rate for specific causes of death did not increase significantly between 2008–2009 (13.5) and 2013–2014 (15.0).
CONCLUSION: Despite the United Nations Millennium Development Goal and a 44% decline in maternal mortality worldwide from 1990 to 2015, maternal mortality has not improved in the United States and appears to be increasing. Maternal mortality rates for women 40 years or older and for nonspecific causes of death were implausibly high and increased rapidly, suggesting possible overreporting of maternal deaths, which may be increasing over time. Efforts to improve reporting for the pregnancy checkbox and to modify coding procedures to place less reliance on the checkbox are essential to improving vital statistics maternal mortality data, the official data source for maternal mortality statistics used to monitor trends, identify at-risk populations, and evaluate the success of prevention efforts.
Maternal mortality is high in the United States and appears to be increasing, with large racial and ethnic disparities; questions about data quality limit interpretation of trends.
Maryland Population Research Center, University of Maryland, and the Department of Family Science, University of Maryland School of Public Health, College Park, Maryland; and the Department of Community Health Sciences, Boston University School of Public Health, Boston, Massachusetts.
Corresponding author: Marian F. MacDorman, PhD, Research Professor, Maryland Population Research Center, 2015 Morrill Hall, University of Maryland, College Park, MD 20742; email: firstname.lastname@example.org.
Marian F. MacDorman's work received partial funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development grant R24-HD041041, Maryland Population Research Center.
Financial Disclosure The authors did not report any potential conflicts of interest.