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.

After approved informed consent, 160 pregnant (term) patients with American society of anaesthesiologist (ASA) physiological status I-II will include this prospective, randomized clinical study. For randomisation of participants, computerized randomisation programme will use and they will divide into 4 groups. Basal value of systolic blood pressure(SBP) and heart rate (HR) will calculate with mean of the measure of 3 time SBP and HR before spinal anaesthesia. Spinal anaesthesia will perform with 5% marcain heavy 2 ml+20 microgram fentanyl at the point of lumbar 3-4 or 4-5 interspinous space to the all patients. After performed spinal anaesthesia, vasopressor infusion will start intravenously. Epinephrine, norepinephrine and phenylephrine will use for vasopressor infusion. 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. Phenylephrine will prepare 100 microg/ml and infusion rate will adjust 30 ml/h for Group P. salin infusion will launch 30 ml/h for group Salin. If systolic blood pressure decrease 20% of basal value or below to 100 mmHg, bolus ephedrine will apply intravenously (IV) for rescue drug. If heart rate will decrease 60 beat per min or 20% of basal value, atropine will apply IV.

At the end of the study all collected data will use for statistically analysis.

Inclusion Criteria:

• ASA I-II physical status
• Pregnant patients
• Full term pregnant

Exclusion Criteria:

• ASA III-IV physical status
• Emergency status
• Heart disease
• Hypertension
• Body mass index>25

pregnant patients

Partipicants and care providers will not known which medication will apply.