Trends and Social Inequalities in Maternal Mortality in the United States, 1969-2018

BACKGROUND: Despite the previous long-term decline and a recent increase in maternal mortality, detailed social inequalities in maternal mortality in the United States (US) have not been analyzed. This study examines trends and inequalities in US maternal mortality by maternal race/ethnicity, socioeconomic status, nativity/immigrant status, marital status, area deprivation, urbanization level, and cause of death. METHODS: National vital statistics data from 1969 to 2018 were used to compute maternal mortality rates by sociodemographic factors. Mortality trends by deprivation level were analyzed by using census-based deprivation indices. Rate ratios and log-linear regression were used to model mortality trends and differentials. RESULTS: Maternal mortality declined by 68% between 1969 and 1998. However, there was a recent upturn in maternal mortality, with the rate increasing from 9.9 deaths/100,000 live births in 1999 to 17.4 in 2018. The large racial disparity persisted over time; Black women in 2018 had a 2.4 times higher risk of maternal mortality than White women. During 2013-2017, the rate varied from 7.0 for Chinese women to 42.0 for non-Hispanic Black women. Unmarried status, US-born status, lower education, and rural residence were associated with 50-114% higher maternal mortality risks. Mothers in the most-deprived areas had a 120% higher risk of mortality than those in the most-affluent areas; both absolute and relative disparities in mortality by deprivation level widened between 2002 and 2018. Hemorrhage, pregnancy-related hypertension, embolism, infection, and chronic conditions were the leading causes of maternal death, with 31% of the deaths attributable to indirect obstetric causes. CONCLUSIONS AND GLOBAL HEALTH IMPLICATIONS: Despite the steep long-term decline in US maternal mortality, substantial racial/ethnic, socioeconomic, and rural-urban disparities remain. Monitoring disparities according to underlying social determinants is key to reducing maternal mortality as they give rise to inequalities in social conditions and health-risk factors that lead to maternal morbidity and mortality.