Inclusion Criteria:  Women undergoing cesarean section under spinal anesthesia Aged ≥19 years and > 40 years . Gestational age ≥ 37 Weeks . Informed Consent From the Patient .  Exclusion Criteria:  Body mass index (BMI) ≥40 kg/m2 .. History of recent opioid exposure . Hypersensitivity to any of the drugs used in the study . Significant cardiovascular, renal, or hepatic disease.