Prediction of vaginal birth after cesarean using information at admission for delivery: a calculator without race or ethnicity

William A. Grobman, Grecio J. Sandoval, Madeline Murguia Rice, Suneet P. Chauhan, Rebecca G. Clifton, Maged M. Costantine, Kelly S. Gibson, Torri D. Metz, Samuel Parry, Uma M. Reddy, Dwight J. Rouse, George R. Saade, Hyagriv N. Simhan, John M. Thorp, Alan Tita, Lynn M. Yee, Monica Longo, Mark B. Landon