[1] Gynecol Ohio State Univ, Dept Obstet, 395 W 12 Ave,Floor 5, Columbus 43210, OH USA
[2] Northwestern Univ, Dept Obstet & Gynecol, Chicago, IL USA
[3] Ohio State Univ, Dept Obstet & Gynecol, Columbus, OH USA
[4] Indiana Univ, Dept Biostat, Indianapolis, IN USA
[5] RTI Int, Durham, NC USA
[6] Gynecol Case Western Reserve Univ, Dept Obstet, Cleveland, OH USA
[7] Univ Pittsburgh, Dept Obstet & Gynecol, Pittsburgh, PA USA
[8] Columbia Univ, Dept Obstet & Gynecol, New York, NY USA
[9] Univ Utah, Dept Obstet & Gynecol, Salt Lake City, UT USA
[10] Univ Penn, Dept Obstet & Gynecol, Philadelphia, PA USA
[11] Eastern Virginia Med Ctr, Dept Obstet & Gynecol, Norfolk, VA USA
[12] Univ Calif Irvine, Sch Med, Dept Obstet & Gynecol, Orange, CA USA