 This position does not use gravity but still holds an advantage over the lithotomy position, as it does not position the vena cava under the uterus, which decreases blood flow to mother and child.In the lithotomy position, the mother is lying on her back with her legs up in stirrups and her buttocks close to the edge of the table.This position is convenient for the caregiver because it permits him or her more access to the perineum.