The success of VBAC depends on several factors. They are- if  there is  any history of  previous uterine rupture, how many cesarean the patient had, how is the uterine incision on previous cesarean, how big is the fetus,when was the last birth, is there any vaginal delivery previously. Proper history of the patient and proper monitoring is needed during labor. VBAC should be performed in a well equipped hospital and trained medical personnel should be available.