Exploring Trends in Severe Maternal Morbidity in the U.S.

The incidence of severe maternal morbidity (SMM) in the U.S. has been rising among mothers over time, with especially pronounced increases among Black mothers. In this paper, we examine why this might be happening. Previous literature takes a limited-scope approach by focusing on select variables as determinants of SMM. We take a broader approach and evaluate the contributions of a large set of variables over a long time span to let the data inform us what factors may be most influential in determining SMM. We use inpatient data from 1998-2019 to see how maternal, hospital, and county-level characteristics may be associated with both the rising trends and the racial disparity in SMM. Decomposition methods show that the observed characteristics explain very little of the overall variation of SMM, but account for a substantial share of the Black-White SMM gap. Medical and pregnancy-related comorbid conditions are the largest drivers of the observed variations. The associational findings indicate that focusing on patients with comorbid conditions and delving more deeply into the features of hospital environments may help researchers identify policy-relevant drivers of SMM and SMM disparities.