Comparison of Two Doses of Norepinephrine in Preventing Hypotension After Spinal Anesthesia

Inclusion Criteria: * Elective or semi-urgent CD under spinal anesthesia * Age over 18 years * Healthy singleton pregnancy beyond 36 weeks' gestation * American Society of Anesthesiologists (ASA) physical status classification 2 * Weight 50 to 100 kg, and height 150 to 180 cm Exclusion Criteria: * Emergency CD red code ( extraction time \<15 min) * Allergy or hypersensitivity to norepinephrine or sulfite * Preexisting or pregnancy-induced hypertension, preeclampsia, eclampsia, the use of cardiac medication or medication for blood pressure control * multiple gestation * Cardiovascular or cerebrovascular disease * Fetal abnormalities * Suspicion of abnormal placentation * History of diabetes mellitus (excluding gestational diabetes) * Use of monoamine oxidase inhibitors, triptyline or imipramine antidepressants * documented history of postoperative nausea and vomiting, previous gastric bypass surgery, history of chronic opioid use (chronic pain syndrome) * Patient refusal