a uterine scar from a previous cesarean section is the most common risk factor. (in one review, 52% had previous cesarean scars.) other forms of uterine surgery that result in full-thickness incisions (such as a myomectomy), dysfunctional labor, labor augmentation by oxytocin or prostaglandins, and high parity may also set the stage for uterine rupture. in 2006, an extremely rare case of uterine rupture in a first pregnancy with no risk factors was reported.