The majority of maternal deaths occur in the postpartum period. We sought to compare postpartum readmission by race and ethnicity to better understand whether there are disparities in maternal health in the postpartum period as indicated by readmission to the hospital. This study aimed to use state-wide Maryland data to identify postpartum readmission rates by race and ethnicity, as well as the major risk factors, indications, and timing of readmission. In this retrospective study (2016-2019), childbirth hospitalizations for patients of childbearing age were identified from the Maryland State Inpatient Database, Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality. Indication for readmission was described. Multivariable logistic regression models were employed to determine racial and ethnic differences in postpartum readmissions, adjusting for maternal and obstetrical characteristics. Among total deliveries (n=260,778), 3914 patients (1.5%) were readmitted within 60 days of delivery. The most common primary diagnoses at readmission were hypertension and infection. The prevalence of readmission was 1.2% (1306/111,325) for White patients, 2.3% (1786/79,412) for Black patients, 1.2% (485/40,862) for Hispanic patients and 1.2% (337/29,179) for patients of Other race or ethnicity (P<.0001). Black patients had the highest rates of readmission for hypertensive disorders as compared with all other races (37%, P<.0001). In adjusted models, Black patients were more likely to be readmitted than White patients (odds ratio, 1.64; confidence interval, 1.52-1.77). The majority of all readmissions occurred in the first week after delivery with Black patients having higher rates of readmission in the second week relative to all other groups (P<.0001). Hypertension is a leading cause of postpartum readmission in Maryland. Black patients were more likely to be readmitted for hypertensive disorders of pregnancy and to have delayed readmission relative to other race or ethnic groups. Maryland public health officials should address disparities with interventions targeting racial and ethnic minorities, patients at risk for hypertensive disorders, and barriers to timely care.