[1] Seoul Natl Univ, Dept Obstet & Gynecol, Coll Med, Seoul 110744, South Korea
[2] NICHD, Perinatol Res Branch, Program Perinatal Res & Obstet,NIH,DHHS, Div Intramural Res,Eunice Kennedy Shriver Natl In, Bethesda, MD USA
[3] NICHD, Perinatol Res Branch, Program Perinatal Res & Obstet,NIH,DHHS, Div Intramural Res,Eunice Kennedy Shriver Natl In, Detroit, MI USA
[4] Univ Michigan, Dept Obstet & Gynecol, Ann Arbor, MI 48109 USA
[5] Michigan State Univ, Dept Epidemiol & Biostat, E Lansing, MI 48824 USA
[6] Wayne State Univ, Ctr Mol Med & Genet, Detroit, MI USA
[7] Seoul Natl Univ, Dept Obstet & Gynecol, Seoul Metropolitan Govt, Boramae Med Ctr, Seoul, South Korea
[8] Wayne State Univ, Sch Med, Dept Obstet & Gynecol, Detroit, MI 48201 USA