Decomposing the Black-White Racial Disparity in Severe Maternal Morbidity Risk: The Role of Hypertensive Disorders of Pregnancy

Background:To our knowledge, no studies have explicitly studied the role of hypertensive disorders of pregnancy (HDP) in racial disparities in severe maternal morbidity (SMM).Methods:Using causal mediation models, we estimated the proportion of the non-Hispanic (NH) Black-White racial disparity in risk of SMM that is explained through the pathway of HDP. We linked 2006-2019 Georgia hospital discharge records with vital statistics birth and fetal death records for NH Black and NH White birthing persons. We used G-estimation of a structural nested mean model to decompose the absolute racial disparity in the incidence of SMM into pathways operating through HDP.Results:NH Black birthing people experienced an excess 56 SMM events (95% confidence interval [CI] = 52, 59) per 10,000 delivery hospitalizations compared with NH White birthing people. If counterfactual disparity measure estimation assumptions hold, the estimated absolute disparity remaining after blocking the causal pathways through HDP was 41 SMM events per 10,000 deliveries (95% CI = 38, 44), suggesting that 26% (95% CI = 12, 40) of the absolute racial disparity would be eliminated if there was no contribution of HDP to SMM risk.Conclusion:Our results are consistent with the hypothesis that intervening to prevent HDP is an important (yet incomplete) pathway for reducing the excess risk among NH Black pregnancies compared with NH White pregnancies.