Does Information Available at Delivery Improve the Accuracy of Predicting Vaginal Birth after Cesarean? Validation of the Published Models in an Independent Patient Cohort - Costantine, Maged M; Fox, Karin A; Pacheco, Luis Diego; Mateus, Julio; Hankins, Gary D.V.; Grobman, William A; Saade, George R (American Journal of Perinatology, 2011)