IRCT20190627044040N1 IRCT 2019-08-25 Zahedan University of Medical Sciences The effect of melatonin on pain after cesarean section Evaluation of different doses of melatonin effect on post operation pain score in patients who underwent cesarean section with spinal anesthesia 2019-08-12 anticipated 150 Complete https://irct.ir/trial/41085 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Used, Assignment: Parallel, Purpose: Treatment, Randomization description: In order to randomization we will use the block method, Accordingly, the patients under study are divided into three groups. The allocation of patients in two groups was based on demographic characteristics and their matching. Based on this, after considering the patients' demographic data, patients were divided into two equal groups of patients, they enrolled in the study and performed desired intervention on them, Blinding description: This means that patients in groups do not know the used drugs, and drugs has similar packaging. 3 Pain after elective cesarean section. Intervention 1: Intervention group: In the first group, oral melatonin 1.5 mg is used 2 hours before spinal anesthesia. Intervention 2: Intervention group: In second group, oral melatonin 3 mg is used 2 hours before spinal anesthesia. Intervention 3: Control group: In third group, placebo is used 2 hours before spinal anesthesia. 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 No more information