Study aim: Effect of pre-spinal anesthesia intravenous fluid therapy on the incidence of post-dural puncture headache and hemodynamic disturbances in cesarean section patients Design: • Type: Single-blind randomized controlled trial (RCT) • Groups: Two groups (Intervention vs. Control) • Randomization: Block randomization or random table method • Blinding: Patients are blinded to group assignment. IV fluids are prepared in identical, coded bags. The anesthesiologist and outcome assessors are also blinded to group allocation. Settings and conduct: • Setting: Amir-al-Momenin Hospital, labor ward and operating room • Methods: • Patients are evaluated preoperatively and provide informed consent • Intervention group: receives IV crystalloid [10–15 ml/kg] prior to spinal anesthesia • Control group: receives fluids only as clinically indicated • Outcomes: Hemodynamic parameters recorded in the operating room; post-dural puncture headache assessed at 24, 48 hours, and day 3 postoperatively Participants/Inclusion and exclusion criteria: • Pregnant women scheduled for cesarean section, aged 18–45 years • ASA physical status I–II • Provided informed consent for participation Intervention groups: 1. Intervention group: Receive intravenous crystalloid [10–15 ml/kg] over 15–20 minutes before spinal anesthesia. 2. Control group: No prophylactic preloading; fluids are given only as clinically indicated. Main outcome variables: • Primary outcome: Incidence of PDPH at 24, 48 hours, and day 3 postoperatively, assessed by patient report and VAS (0–10). • Secondary outcome: Hemodynamic disturbances, defined as ≥20% drop in systolic BP or MAP <65 mmHg, and requirement for vasopressors, recorded intraoperatively.