The overall goal: to determine the prevalence of shivering after spinal anesthesia for caesarean section in groups of midazolam, midazolam - ketamine and ketamine. Study design: Randomized, single-blind, placebo-controlled. The study population: consists of patients who were referred for elective cesarean section Fatemieh Hospital operating room in Hamadan City Inclusion criteria: (a) Age 18-40 years and undergoing cesarean section; (b) ; physical status class I or II in accordance with anesthesia; (c) Term pregnancy (gestational age 36-40 weeks); (d) Singleton pregnancy. Exclusion criteria: (a) High-risk pregnancy; (b) Preeclampsia;(c) A history of cardiovascular disease, lung disease, mental, thyroid disease, diabetes mellitus type 1 and 2;(d) needs to blood or blood supply transfusion;(e) Fever over 38 ° C;(f) Drag over an hour during surgery;(g) A history of nausea and vomiting to Previous surgery;(h) Patients with spinal anesthesia ban. The sample size:In this study, 31 patients in each group is examined. Intervention or interventions studied: Patients were randomly divided into four groups A Midazolam75 µg / kg, Group B ketamine 0/5mg / kg, Group C ketamine0/25 mg / kg + 37/5μg / kg midazolam and Group D (control group) received normal saline 9/0% divided. Drugs after clamping the umbilical cord is injected intravenously. Shivering will be evaluated by crosly scale and sedation score will be evaluated by Ramsay sedation scale. Primary outcome or outcomes studied: Side effects such as nausea and vomiting after surgery, Changes in blood pressure and heart rate, arterial oxygen saturation and hallucination will be reviewed and evaluated at the end of the above parameters.