<prompt> Placenta previa mouth is associated with all of the following except:Large placentaPrevious C. S. scarPrimigravidaPrevious placenta previa  <response>: Placenta previa is implantation of the placenta partially or completely over the lower uterine segment. Damage to the endometrium or myometrium due to previous surgery or infection can predispose to low implantation and placenta previa.Risk factors for placenta previa:Prior surgery cesarean section Myomectomy HysterotomyPrevious uterine curettageEndometritisIncreasing maternal age 35 yearsIncreasing parityPlacental size increased as in multiple pregnancyPlacental abnormality Succenturiate lobeSmoking due to defective decidual vascularisationElevated prenatal maternal serum alpha fetoprotein levels unexplained 