Objective
This study evaluated the interplay of blood pressure(BP) patterns during hospital admission for labour and delivery and the risk of postpartum readmission for hypertension.
Study design
We conducted a retrospective cohort study of 17 587 individuals who delivered at a large women’s specialty hospital in Louisiana between 1 January 2017 and 1 March 2020.1 Previous reports from this cohort found increased risk for postpartum readmission for hypertension with black race, pre-eclampsia, government health insurance, from mild BP elevations at admission and early postpartum.1 BP values were abstracted from the electronic medical record at two clinical time points: admission for delivery and approximately 36-hour postpartum. Patients were categorised into four groups at each time point based on their highest systolic or diastolic BP: <130/<80 mm Hg (group 1), 130–139/80–89 mm Hg (group 2), 140–149/90–99 mm Hg (group 3), and ≥150/≥100 mm Hg (group 4). These groupings were used to create a matrix for evaluating the relationship between BP trajectories during delivery hospitalisation and the risk of postpartum readmission for hypertension within 30 days of discharge. Analyses were conducted using R statistical software V.4.0.2. CIs for the proportion of readmissions for hypertension in groups were determined using z tests of proportions for combinations with ≥100 patients. Patients or the public were not involved in the design, or conduct, or reporting, or dissemination plans of our research.
Results
Figure 1 illustrates the relationship of BP across the labour and delivery hospitalisation and associated risk for postpartum readmission for hypertension by organising ‘admit BP’ groups and ‘36-hour postpartum BP’ groups into a 16-combination matrix. The colour gradient depicts the trend of readmission rates (darker colours signifying higher readmission rates and lighter colours signifying the opposite). Rates for readmission increase in a stepwise manner from the lowest (group 1) to the highest (group 4) BP grouping at both admission for delivery and at 36-hour postpartum. The highest readmission rates were seen in the following three group combinations: patients who fell in both admit BP group 3 and 36-hour postpartum BP group 3 (per cent group readmission for hypertension rate: 5.4%; 95% CI 3.5% to 8.1%); patients who fell in admit BP group 4 and 36-hour postpartum group 2 (7.1%; 95% CI 5.4% to 10.2%); and patients who fell in admit BP group 4 and 36-hour postpartum group 3 (7.4%; 95% CI 5.4% to 10.2%) (figure 2).
Matrix for admit blood pressure (BP) and 36-hour postpartum (PP) BP. In each cell, we report total number of readmissions/total number of patients = per cent readmission (95% CI). DPB, diastolic blood pressure; SBP, systolic blood pressure.
Percent increase of readmission rate across select groups of patients readmitted for hypertension within 30 days postpartum (PP), stratified by combined admission and 36-hour PP blood pressure (BP) groups. The highest readmission rates were observed in patients with elevated BP at one or both time points, particularly in the group 4/2 and group 4/3 combinations (≥7%). Patients in group 1/1 had the lowest readmission rate (0.6%).
Conclusion
Our study findings illustrate that BP trends across the delivery hospital stay are useful clinical considerations when assessing the risk of severe postpartum hypertension. Findings specifically within the mild hypertension categories (ie, group 2) are particularly insightful, as increased attention to these readings across the delivery would encourage the identification of patients at risk that may not be otherwise identified. For example, those in the admit/36-hour postpartum BP group 2/2 (2.2%, 1.6–3.0%) who experience mildly elevated BP on admission and early after delivery have a threefold increased risk for readmission compared with the normotensive group (1/1). The timing of the postpartum BP measurement (approximately 36 hours after delivery) was selected intentionally over the classically reported BP at discharge to give clinicians the opportunity to intervene prior to discharge, be it with antihypertensive therapy, remote BP monitoring or both. The findings of this study support the consideration of BP trends across delivery and the application of lower BP thresholds when assessing the risk of postpartum readmission for hypertension.
JCN, JHC and EFS contributed equally.
Contributors: JCN and EFS contributed equally to the conception, design, data acquisition, analysis and interpretation of the data. JCN, EFS and JHC contributed equally to the drafting of the manuscript. All authors reviewed and approved the final version of the manuscript and agree to be accountable for all aspects of the work. EFS is the guarantor of this study and accepts full responsibility for the integrity of the data and the accuracy of the analysis.
Funding: The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests: None declared.
Patient and public involvement: Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review: Not commissioned; externally peer reviewed.
Ethics statements
The study was approved by the institutional review board (IRB) of the Woman’s Hospital Foundation (FWA00005699) with waivers of informed consent and Health Insurance Portability and Accountability Act authorisation granted (study ID RP-20-001). The study was conducted in accordance with relevant guidelines and regulations as stipulated by the IRB.
Taylor K, Pochana SS, Chapple AG, et al. Blood pressure during hospital stay for delivery and risk for postpartum readmission for hypertension. O&G Open 2024; 1:030.
