This is a randomized, placebo-controlled trail, the objective of this study is observation the effect of sub hypnotic dose of propofol for prevention of nausea and vomiting induced by hemabate during spinal anesthesia for elective cesarean section. The primary outcome is the presence of post-delivery intra-operative nausea and vomiting in parturients. The patients demographic characteristics, blood pressure, sensory block level, and the medications will be collected.