The level of spinal anesthesia in obstetric patients had been investigated in several studies. Increased cephalad spread of local anesthetics had been demonstrated with increased intra-abdominal pressure, changes in anteroposterior spinal curves and lumbar lordosis. Theoretically the body shape might have contribution to the above factors and might have influence on the spinal level. In this research we plan to investigate the relationship of abdominal circumference, trunk length and the level of spinal anesthesia in obstetric patients during Cesarean section. Only those C/S patients indicated and scheduled for spinal anesthesia will be observed. The spinal anesthesia will be performed as routine practice. This study will not change the clinical plan in any aspect. We will only passively record the abdominal circumference, trunk length and the level of spinal anesthesia and calculate the correlation between them.