[1] Brown Univ, Dept Obstet, Providence, RI USA
[2] Brown Univ, Dept Gynecol, Providence, RI USA
[3] Univ Texas Med Branch, Galveston, TX USA
[4] Ohio State Univ, Columbus, OH USA
[5] Case Western Reserve Univ, Cleveland, OH USA
[6] Univ Alabama Birmingham, Birmingham, AL USA
[7] Univ N Carolina, Chapel Hill, NC USA
[8] Univ Utah, Hlth Sci Ctr, Salt Lake City, UT USA
[9] Columbia Univ, New York, NY USA
[10] Boston Med Ctr, Boston, MA USA
[11] Univ Pittsburgh, Pittsburgh, PA USA
[12] Duke Univ, Durham, NC USA
[13] Univ Colorado, Sch Med, Anschutz Med Campus, Aurora, CO USA
[14] Univ Texas Hlth Sci Ctr Houston, Childrens Mem Hermann Hosp, Houston, TX USA
[15] Northwestern Univ, Chicago, IL USA
[16] Stanford Univ, Stanford, CA USA
[17] Univ Texas Southwestern Med Ctr, Dallas, TX USA
[18] Univ Penn, Philadelphia, PA USA
[19] Univ Texas Austin, Austin, TX USA
[20] George Washington Univ, Biostat Ctr, Washington, DC USA
[21] Eunice Kennedy Shriver Natl Inst Child Hlth & Hum, Bethesda, MD USA