Variations in Postpartum Readmission by Individual Race, Ethnicity, and Rurality in South Carolina.

Importance: Racial and ethnic disparities in postpartum readmission (PPR) remain a critical public health concern, with non-Hispanic Black individuals experiencing rates up to 3 times as high as non-Hispanic White individuals. PPR is often associated with mental health disorders (MHDs) and substance use disorders (SUDs), and barriers to care are particularly acute in rural communities. Objective: To investigate intersections in the associations of individual residential rurality and race and ethnicity with all-cause, MHD-, and SUD-related PPR throughout 1 year post partum. Design, Setting, and Participants: This statewide retrospective cohort study used data from birth certificates linked to all-payer hospital data for individuals 15 to 50 years of age who gave birth and were discharged from South Carolina hospitals between January 1, 2018, and December 31, 2021. Data analyses were completed August 17, 2025. Exposures: Individual race and ethnicity and individual residential location at time of birth. Main Outcomes and Measures: Cumulative incidence of all-cause, MHD-, and SUD-related PPR at 42, 90, 180, and 365 days post partum. Cox proportional hazards models estimated adjusted hazard ratios (AHRs) and 95% CIs for 1-year follow-up, adjusting for individual characteristics. Results: Of 190 645 births to 166 330 unique individuals (mean [SD] age, 28.2 [5.8] years; 4.9% Hispanic, 30.9% non-Hispanic Black, and 57.1% non-Hispanic White), the highest percentage (30.4%) included individuals between 25 and 29 years of age; 27 961 (14.7%) of births were to women residing in rural areas and 162 684 (85.3%) of births were to women residing in urban areas. Up to 1 year post partum, 4.7% of birthing individuals had all-cause PPR, 1.5% had MHD-related PPR, and 0.8% had SUD-related PPR. In adjusted models, non-Hispanic Black individuals had higher risk of all-cause PPR compared with non-Hispanic White individuals in urban areas (AHR, 1.38 [95% CI, 1.31-1.45]), whereas Hispanic individuals had lower risk (AHR, 0.83 [95% CI, 0.74-0.93]). Rural residence was associated with increased all-cause PPR risk overall (AHR, 1.15 [95% CI, 1.06-1.25]) but was also associated with reduced racial and ethnic disparities in all-cause PPR (interaction AHR, 0.86 [95% CI, 0.77-0.97] for non-Hispanic Black compared with non-Hispanic White, and interaction AHR, 0.55 [95% CI, 0.34-0.89] for Hispanic compared with non-Hispanic White). Similar patterns were observed for MHD- and SUD-related PPR, although rural interactions were not statistically significant. Conclusions and Relevance: In this cohort study of individuals giving birth in South Carolina, racial and ethnic disparities associated with PPR were pronounced among urban residents and attenuated in rural areas, suggesting that geographic context may modify these disparities.