Activity restriction among women with a short cervix

William A. Grobman, Sharon A. Gilbert, Jay D. Iams, Catherine Y. Spong, George Saade, Brian M. Mercer, Alan T.N. Tita, Dwight J. Rouse, Yoram Sorokin, Kenneth J. Leveno, Jorge E. Tolosa, John M. Thorp, Steve N. Caritis, J. Peter Van Dorsten