Epidural Analgesia Duration and Postpartum Blood Pressure Trajectory in Hypertensive Pregnancies: A Time-to-Event...

Postpartum hypertension (PPHTN) drives severe maternal morbidity in women with hypertensive disorders of pregnancy (HDP). The uncharacterized effect of labor epidural analgesia (LEA) on postpartum blood pressure trajectories may explain its protective association with severe maternal morbidity. We aim to investigate whether LEA exposure is associated with a delayed onset of PPHTN during hospitalization in women with HDP.

We conducted a retrospective cohort study of women with HDP from 2018 to 2023. Participants were categorized based on LEA duration, with non-recipients assigned a duration of zero. An optimal LEA duration cut-off was identified using the maximally selected log-rank statistic to facilitate group comparison. The primary outcome was in-hospital PPHTN, defined as ≥2 postpartum blood pressure measurement meeting standard hypertensive criteria. Time-to-event analyses were performed using Kaplan-Meier estimates and the Log rank test. Multivariable Cox regression with DAG-guided covariate selection was used to adjust for potential confounders. Secondary outcomes included postpartum antihypertensive treatment patterns, specifically combination therapy use and daily labetalol dose. Three prespecified sensitivity analyses assessed the robustness of results.

Of 1,069 women included in the final analysis, 823 (77.0%) received LEA. Longer LEA duration was significantly associated with a reduced hazard of PPHTN (HR = 0.96 per hour; 95% CI: 0.93-0.98; P = 0.002). The optimal duration cut-off for discriminating PPHTN risk was 3.5 hours. Women with LEA duration >3.5 hours had lower in-hospital PPHTN incidence, a longer median time to onset, and reduced postpartum antihypertensive requirements, including lower rates of combination therapy and labetalol dosing, while nifedipine use was similar between groups. After multivariable adjustment, LEA >3.5 hours was independently associated with a reduced risk of PPHTN (HR = 0.72; 95% CI: 0.58-0.88; P = 0.001). Sensitivity analyses yielded consistent results in women not requiring postpartum antihypertensive therapy and across gestational hypertension and pre-eclampsia subgroups. In the cause-specific Cox model, LEA >3.5 hours was associated with a lower hazard of PPHTN, consistent with the primary model. Among women receiving postpartum antihypertensives, LEA duration was not significantly associated with PPHTN risk but was linked to lower labetalol doses.

Longer LEA duration was associated with a reduced risk of postpartum hypertension and lower antihypertensive use in women with HDP. These observational findings indicate that prolonged analgesia may be associated with improved postpartum hemodynamic stability, suggesting consideration for its continuation in eligible patients; prospective studies are needed to confirm causality and guide clinical practice.