Vaginal birth or trial of labor after previous cesarean delivery represents one of the most significant changes in obstetric practice. There are numerous reasons that influence the decision to proceed with either a trial of labor after previous cesarean delivery or elective repeat cesarean delivery. For the majority of women with a previous cesarean delivery, a trial of labor should be encouraged. There are few absolute contraindications. Women with a previous classical uterine incision should not undergo a trial of labor and should be delivered once fetal lung maturity is documented. An attempted trial of labor should not be discouraged in women with a previous low vertical uterine incision, although the patient should be counseled that the evidence as to the risks and benefits of a trial of labor is limited. In those situations where the previous uterine incision is unknown, but suggestive of a classical uterine incision, an argument can be made for elective repeat cesarean delivery once fetal lung maturity is documented. When the history of a uterine incision is unknown and unlikely to be classical, a trial of labor can be attempted after counseling. Close intrapartum management is warranted in this situation. The optimal management of labor in women with a previous low transverse uterine incision who desire a trial of labor with a breech presentation, multiple gestation, or in whom induction of labor is necessary is uncertain; the evidence as to the risks and benefits of a trial of labor is limited and obstetric management should be individualized after counseling. Uterine rupture represents the most catastrophic complication of a trial of labor after previous cesarean delivery. In women suspected of having a uterine scar injury, prompt intervention is necessary to minimize both maternal and neonatal complications. Women who are not successful with a trial of labor require repeat cesarean delivery and appear to be at greatest risk for maternal complications. Identifying those women most likely to be successful with an attempted trial of labor after previous cesarean while also incurring the least maternal and perinatal morbidity and mortality would be ideal. At present, however, there is no sufficiently predictive method to identify those women most likely to benefit from an elective repeat cesarean delivery. The management of labor in women with a previous uterine scar is not low risk. As the number of women who attempt vaginal birth after previous cesarean delivery increases, we should focus on trying to develop reliable methods of identifying women who should and should not undertake a trial of labor after cesarean delivery.
