[1] Seoul Natl Univ, Dept Obstet & Gynecol, Coll Med, Seoul, South Korea
[2] Dankook Univ, Cheil Gen Hosp & Womens Healthcare Ctr, Dept Obstet & Gynecol, Coll Med, Seoul, South Korea
[3] Univ Ulsan, Dept Obstet & Gynecol, Asan Med Ctr, Coll Med, Seoul, South Korea
[4] Sungkyunkwan Univ, Dept Obstet & Gynecol, Samsung Med Ctr, Sch Med, Seoul, South Korea
[5] Yonsei Univ Hlth Syst, Yonsei Univ, Inst Womens Life Med Sci, Dept Obstet & Gynecol,Coll Med, Seoul, South Korea
[6] CHA Univ, Dept Obstet & Gynecol, CHA Gangnam Med Ctr, Seoul, South Korea
[7] Korea Univ, Dept Obstet & Gynecol, Coll Med, Seoul, South Korea
[8] Konkuk Univ, Dept Obstet & Gynecol, Sch Med, Seoul, South Korea
[9] Seoul Natl Univ, Dept Obstet & Gynecol, Seoul Metropolitan Govt, Boramae Med Ctr, Seoul, South Korea
[10] Ewha Womans Univ, Dept Obstet & Gynecol, Seoul, South Korea
[11] CHA Univ, Dept Obstet & Gynecol, Bundang CHA Med Ctr, Sch Med, Seongnam, South Korea
[12] Catholic Univ Korea, Dept Obstet & Gynecol, Coll Med, Seoul, South Korea
[13] Ewha Womans Univ, Dept Hlth Convergence, Seoul, South Korea