Impact of Circadian Rhythm on Hypotension During Spinal Anesthesia for Cesarean Delivery: A Prospective Observational Study

Background: Spinal anesthesia (SA) is the preferred method for cesarean delivery, though it is often associated with maternal hypotension. Predicting hypotension can enhance clinical decision-making, optimize management strategies, and improve patient outcomes. Aim: We aimed to test the association between circadian rhythm and the incidence of hypotension during spinal anesthesia for cesarean delivery. Patients and Methods: This prospective observational study included women undergoing cesarean delivery with spinal anesthesia, excluding those with inadequate anesthesia or major comorbidities. Patients were divided into morning (6:00-12:00) and afternoon (12:00-18:00) groups based on C-section time. Hemodynamic variables, total ephedrine dosage, and incidence of nausea, vomiting, and hypotension were assessed, with hypotension as the primary outcome. Results: Out of 231 screened patients, 203 were enrolled, and 200 patients were analyzed. 114 were allocated to Group morning and 86 to Group afternoon. The overall incidence of hypotension was 66%, with severe hypotension occurring at a significantly higher rate in the morning group compared to the afternoon group (43% vs. 30.2%, P = 0.028). Conclusion: Our findings suggest that the timing of cesarean delivery may influence the incidence of spinal anesthesia-induced hypotension, underscoring the potential clinical value of considering circadian factors when scheduling procedures to optimize maternal hemodynamic stability.