Postpartum emergency department visits and readmissions in the 90 days after a singleton delivery.

INTRODUCTION: Maternal morbidity and mortality are often concentrated in the first 90 days postpartum. Postpartum emergency department (ED) and hospital use provide valuable insight into peripartum health outcomes. We performed a health system-wide analysis of sociodemographic, clinical, and hospital-level factors associated with 90-day postpartum ED visits and inpatient hospital admissions. METHODS: This retrospective cohort study of all 90-day postdelivery ED visits or inpatient admissions, referred to as "90-day postpartum hospital use," in a nine-hospital Midwest health system included all births from January 2018 to June 2023. We applied a multilevel eco-social framework to examine associations between factors within three domains and 90-day postpartum hospital use. Exposure variables included sociodemographic factors (age, race/ethnicity, insurance, language, census zip code percent poor households), clinical factors (parity, clinical risk factors, body mass index [BMI], severe maternal morbidity during delivery admission [SMM], and other birth outcomes), and hospital type. We applied univariable and multivariable Poisson regression analyses. RESULTS: Of 104,076 deliveries, 6879 (6.6%) were followed by 90-day postpartum hospital use (ED visit n = 4559; hospital admission n = 2812). In bivariate analysis, all risk factors were significant. Chronic hypertension, substance use disorder, BMI ≥ 40 kg/m2, and SMM had the highest rates of 90-day postpartum hospital use. After adjusting for all factors under investigation, Medicaid insurance (adjusted incidence rate ratio [aIRR] 1.43; 95% confidence interval [CI] 1.34-1.45), non-Latinx Black race (aIRR 1.35; CI 1.25-1.46) SMM (aIRR 1.95; 95% CI 1.75-2.18), chronic hypertension (aIRR 1.59; CI 1.49-1.70), and BMI ≥ 40 kg/m2 (aIRR 1.52; CI 1.36-1.70) were associated with the greatest 90-day postpartum hospital use risk compared to the reference categories. Primiparity and all other medical comorbidities had relatively weaker associations. Delivery at an exurban or community hospital was associated with greater 90-day postpartum hospital use risk than delivery at the academic medical center. CONCLUSION: In this health system-wide analysis, 90-day postpartum hospital use is associated with a combination of sociodemographic, clinical, and hospital factors, underscoring the need for a comprehensive mitigation strategy.