Risk factors for emergency department visits and readmissions for postpartum hypertension

Postpartum hypertension accounts for 15 to 20% of postpartum Emergency Department (ED) visits and readmissions in the United States. Postpartum readmission is a quality metric and target of quality improvement as it indicates poor control of hypertension and can portend increased morbidity. We aim to evaluate risk factors for postpartum ED visits and readmissions for hypertension.

This was a retrospective cohort study of all birthing patients with peripartum hypertension at a single tertiary care center over a 5-year period (2017-2022). Inclusion criteria were age 18 years or above, existing diagnosis of chronic hypertension or hypertensive disease of pregnancy diagnosed during the intrapartum or postpartum course, and both delivery and ED visit or readmission at the study institution. Maternal baseline and intrapartum characteristics were chart abstracted. Primary outcome was ED visit or readmission (EDR) for postpartum hypertension. Patients who had EDR within 42 days of delivery were compared to those who underwent routine outpatient surveillance. For all analyses, p values were two-way, and the level of statistical significance was set at p < 0.05.

Of 16,162 patients who gave birth during the study period, 2403 (14.9%) patients met the definition of peripartum hypertension. 218 (9.1%) presented to the ED or were readmitted for hypertension. Risk factors for EDR were as follows: maternal age ≥40 years (22.9% vs 15.3%, p = 0.003), prenatal aspirin use (6.9% vs 3.9%, p = 0.039), cesarean delivery (42.7% vs 35.8%, p = 0.044), chronic hypertension (37.2% vs 31.6%, p = 0.029), preeclampsia with severe features (32.6% vs 15.6%, p < 0.001), postpartum hemorrhage (22.9% vs 12.0%, p < 0.001), and intrapartum need for intravenous anti-hypertensives (23.9% vs 3.3%, p < 0.001). Factors at discharge that increased risk of EDR included prescription of anti-hypertensives at discharge (27.5% vs 8.6%, p < 0.001) and having >50% elevated blood pressures within the 24 h prior to discharge (16.5% vs 11.9%, p = 0.046). In a multivariable logistic regression controlling for prenatal aspirin use, mode of delivery, postpartum hemorrhage, and chorioamnionitis, a higher risk of EDR remained for maternal age ≥40 years (aOR, 1.56; 95% confidence interval (CI), 1.11-2.20; p = 0.011), PO anti-hypertensives at discharge (aOR, 4.05; 95% CI, 2.86-5.73; p < 0.001), preeclampsia with severe features (aOR, 2.50; 95% CI, 1.83-3.42; p < 0.001), and history of IV anti-hypertensive exposure (aOR, 9.30; 95% CI, 6.20-13.95; p < 0.001).

Maternal age of 40 years and above, chronic hypertension, preeclampsia with severe features, prescription of anti-hypertensives on discharge, and elevated blood pressures leading up to discharge are associated with postpartum ED visits or readmissions for hypertension. Risk factor identification can aid in the development of predictive tools to determine high risk groups and interventions to reduce ED visits and readmissions.