In this ecological study, we examined the associations between state-level income inequality and pregnancy-related mortality among non-Hispanic (NH) black and NH white populations across the US. We estimated total population and race-specific 5-year pregnancy-related mortality ratios in each state based on national death and live birth records from 2011 to 2015. We obtained data on Gini coefficients for income inequality and population-level characteristics from the US Census American Community Survey. Poisson regression with robust standard errors estimated pregnancy-related mortality rate ratios (RR) and 95% confidence intervals (CI) associated with a one unit increase in income inequality overall and separately within black and white populations. Adjusted linear regression models estimated the associations between income inequality and magnitude of the absolute and relative racial inequity in pregnancy-related mortality within states. Across all states, increasing contemporaneous income inequality was associated with a 15% and 5-year lagged inequality with 14% increase in pregnancy-related mortality among black women (aRR = 1.15, 95% CI = 1.05; 1.25 and aRR = 1.14, 95% CI = 1.04; 1.24, respectively) after controlling for states' racial compositions and socio-economic conditions. In addition, both lagged and contemporaneous income inequality were associated with larger absolute and relative racial inequities in pregnancy-related mortality. These findings highlight the role of contextual factors in contributing to pregnancy-related mortality among black women and the persistent racial inequity in maternal death in the US.
Keywords: Health disparities; Income inequality; Pregnancy-related mortality; Race.