Effect of Vasopressors on Spinal Anaesthesia Induced Hypotension

160 pregnant patients will be enrolled in this study. Participants will divide in to 4 groups. Spinal anaesthesia will perform with 5% marcain heavy 2 ml+20 microgram fentanyl to the all patients. After performed spinal anaesthesia, vasopressor infusion will be started intravenously. Epinephrine will prepare 5 mg/ml and infusion rate will adjust 30 ml/h for Group E. Norepinephrine will prepare 5 mg/ml and infusion rate will adjust 30 ml/h for Group NE and 0.9% saline (group S) was launched immediately after induction of spinal anesthesia. Phenylephrine will prepare 100 microg/ml and infusion rate will adjust 30 ml/h for Group P. If systolic blood pressure decrease 20% of basal value or below to 100 mmHg, bolus ephedrine will apply intravenously (IV). If heart rate will decrease 60 beat per min or 20% of basal value, atropine will apply IV.