Hypertensive Disorders at Delivery and Postpartum Cardiovascular Morbidity: A Retrospective Cohort Study

OBJECTIVE: To analyse the association between hypertensive diagnoses at delivery-both as a composite and individual diagnoses-and subsequent postpartum readmission for cardiovascular severe maternal morbidity (SMM). DESIGN: Retrospective cohort study. SETTING: 2016-2022 Nationwide Readmissions Database. POPULATION OR SAMPLE: Delivery hospitalisations with subsequent 6-month postpartum readmissions with cardiovascular SMM. METHODS: Multivariable logistic regression models were performed for postpartum cardiovascular SMM with delivery hospitalisation hypertensive diagnoses as the exposure of interest. Adjusted odds ratios (aORs) accounting for demographic, clinical and hospital factors were estimated as measures of association. An ancillary analysis restricted to deliveries with hypertensive diagnoses, excluding preterm prelabour rupture of membranes and preterm labour was performed to analyse the effect of gestational age at delivery. MAIN OUTCOME MEASURES: Composite cardiovascular SMM. RESULTS: Among 12.0 million delivery hospitalisations, 1.8 million (15.4%) had an associated hypertensive diagnosis at delivery. Overall, 14 297 individuals (1.19 per 1000) were readmitted within 6 months postpartum with cardiovascular SMM, of whom 5912 (41.4%) had a hypertensive diagnosis at delivery. Hypertensive diagnoses were associated with increased odds for 6 months postpartum cardiovascular SMM readmission (aOR 2.8 95% CI 2.7-3.0). Evaluating individual diagnoses, superimposed preeclampsia (aOR 4.3, 95% CI 3.8-4.8), chronic hypertension (aOR 3.2, 95% CI 2.9-3.5), preeclampsia without severe features (aOR 3.1, 95% CI 2.8-3.5), preeclampsia with severe features (aOR 3.0, 95% CI 2.7-3.3) and gestational hypertension (aOR 2.1, CI 1.9-2.3) were all associated with significantly higher odds for postpartum cardiovascular SMM readmission compared to the absence of hypertensive diagnoses. In ancillary analysis restricted to patients with hypertensive disorders, delivery < 34 weeks was associated with higher odds for 6-month cardiovascular SMM postpartum readmission (aOR 1.4, 95% CI 1.2-1.6). CONCLUSIONS: Hypertensive diagnoses were associated with significantly increased odds for 6-month postpartum cardiovascular SMM readmission, with individual diagnoses demonstrating distinct odds. Among patients with hypertensive disorders, delivery < 34 weeks was particularly associated with increased odds. Hypertensive disorders are important risk factors for adverse cardio-obstetric outcomes postpartum and represent important factors to identify patient risk and improve the quality of postpartum care.