This study is a double blind clinical trial. One hundred patients admitted for non-emergency cases to Taleghani hospital in Arak. Inclusion criteria: ASA I, II, age: 20-35, BMI: nineteen to twenty-six Exclusion criteria: fetal distress, symptoms for start delivery, multiple pregnancy , hypertension, preeclampsia, intrauterine growth restriction, contraindication for spinal anesthesia, polyhydramnius, macrosomia. In first, researcher obtained demographic information and vital signs and arterial oxygen saturation from all patients. Then, researcher injected Ringer serum 10 ml per kg and 10 mg Metoclopramide and 50 mg Ranitidine, as premedication 15 minutes before surgery. Patients were allocated randomly (simple random) into two groups (pelvic tilt and tilt beds by 15 degrees). Spinal anesthesia was done in the space between the vertebrae of the L3-L4 or L4-L5 with needle 26 and 12.5 mg of Buivacaine injected in 15 seconds in the subarachnoid space. The patients were divided according to their group‘s position. Sensational block was investigated every 1 min after anesthesia and motor block measured by Bromeg scale. Time of sensational block were recorded in T10 and highest Dermatomes block in 15 minutes. Mean arterial blood pressure, heart rate and arterial oxygen saturation were measured every 5 minutes to end of surgery. The fetal Apgar scores were recorded at first and fifth minute after delivery.