IRCT20120915010841N8 IRCT 2018-06-23 Hamedan University of Medical Sciences Determination of effective drug in prevention of post spinal hypotension in C/S Comparison of Intravenous bolus Phenylephrine and Ephedrine for prevention of postspinal Hypotension during Cesarean section. 2017-07-23 anticipated 80 Complete https://irct.ir/trial/29134 interventional Randomization: Randomized, Blinding: Double blinded, Placebo: Not used, Assignment: Parallel, Purpose: Prevention, Randomization description: In this study, the randomization method is used as a 4-blocks. In this way, according to the sample size, 20 blocks of four are identified, and in each of these blocks of four, two of each group will be written in the form of letters A or B. This means that two A and two B are written in each block, although the order of the writing of the four letters A and B will be different in each block. The periodic numbers table will then be used to determine the order of block selection, Blinding description: Ephedrine (10 mg) and phenylephrine (100 μg) in the same volumes (1 ml) are prepared in the same syringes by the anesthetist nurse according to the list of patients entered into the study (based on the four blocks) and then administered intravenously after spinal anesthesia. . Therefore, the anesthetist, the patient and the person evaluating the outcome (anesthetist) are not familiar with the type of prescribed medication. 2-3 post spinal anaesthesia hypotension. Intervention 1: First intervention group : In this group immediately after the spinal anesthesia, 10 mg (1ml) of ephedrine which is a vaoconstrictor for prevetion of hypotension is injected intravenously. Intervention 2: Second intervention group : In this group immediately after the spinal anesthesia, 100 ug (1ml) of ephedrine which is a vaoconstrictor for prevetion of hypotension is injected intravenously. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is Because the study is not finished yet.