[1] UCSD Womens Pelv Med Ctr, La Jolla, CA 92037 USA
[2] Univ Calif San Diego, Dept Reprod Med, San Diego, CA 92103 USA
[3] Univ Alabama, Dept Obstet & Gynecol, Birmingham, AL 35294 USA
[4] Univ Utah, Dept Obstet & Gynecol, Salt Lake City, UT USA
[5] Cleveland Clin, Obstet Gynecol & Womens Hlth Inst, Cleveland, OH 44106 USA
[6] Duke Univ, Med Ctr, Dept Obstet & Gynecol, Durham, NC 27710 USA
[7] Loyola Univ, Dept Obstet & Gynecol, Maywood, IL 60153 USA
[8] Univ Texas Dallas, Dept Obstet & Gynecol, Dallas, TX 75230 USA
[9] Univ Michigan, Dept Biostat, Ann Arbor, MI 48109 USA