[1] Univ Penn, Dept Obstet & Gynecol, Philadelphia, PA 19104 USA
[2] Duke Univ, Med Ctr, Dept Obstet & Gynecol, Durham, NC 27710 USA
[3] Univ Alabama Birmingham, Dept Med, Birmingham, AL 35294 USA
[4] Univ New Mexico, Hlth Sci Ctr, Dept Obstet & Gynecol, Albuquerque, NM 87131 USA
[5] Univ New Mexico, Hlth Sci Ctr, Dept Surg, Albuquerque, NM 87131 USA
[6] Kaiser Permanente, Dept Obstet & Gynecol, San Diego, CA USA
[7] Brown Univ, Alpert Med Sch, Dept Obstet & Gynecol, Providence, RI 02912 USA
[8] Univ Pittsburgh, Med Ctr, Dept Obstet Gynecol & Reprod Sci, Pittsburgh, PA USA
[9] Cleveland Clin, Dept Urol, Cleveland, OH 44106 USA
[10] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, NIH, Bethesda, MD USA
[11] RTI Int, Res Triangle Pk, NC USA