(268) Association between social vulnerability and severe maternal morbidity

Objective: The Social Vulnerability Index (SVI) measures community-level factors associated with health outcomes, but few studies have measured their contribution to perinatal morbidity. We examined the association between SVI and severe maternal morbidity (SMM).

Study Design: We included patients 15-44 years enrolled in Tennessee Medicaid who delivered between 2007-2019. Enrollment files were linked to healthcare encounters and prescription fill data, hospital discharge and birth certificate data. The primary exposure was SVI ranging from 0 to 100 (lower to higher SVI) and assigned based on residential address at delivery. Secondary exposures included SVI subthemes: socioeconomic status, household characteristics, racial and ethnic minority status, and housing type and transportation. The primary outcome was SMM as defined by Centers for Disease Control and Prevention criteria using diagnosis codes for 21 conditions. We employed multivariable logistic regression to estimate the association between SVI and SMM, adjusting for covariates selected a priori. We stratified by race/ethnicity and rural versus metro residence to test whether the association between SVI and SMM varied by these subgroups.

Results: We identified 369,465 births meeting eligibility criteria, of which 8,057 (2.2%) experienced SMM. SVI quartiles were Q1 0-41, Q2 42-67, Q3 68-87, and Q4 87-100. Increasing SVI was associated with increasing odds for SMM (aOR 1.018 [1.013-1.023] per 5 unit increase in SVI). Increasing SVI was associated with SMM for each subtheme except housing type and transportation. When analyses were stratified by Black or non-Black race, SVI was significantly associated with SMM only among Black patients (adjusted OR 1.013 [95% CI 1.004-1.021] per 5 unit increase in SVI). The association between overall SVI and SMM did not vary significantly by rurality.

Conclusion: We demonstrated a positive association between SVI and SMM, especially among Black patients. Greater investment in vulnerable communities may help reduce large disparities in pregnancy outcomes in the United States.