[1] Dongguk Univ, Dept Obstet, Seoul, South Korea
[2] Seoul Natl Univ, Seoul Metropolitan Govt, Dept Family Med, Boramae Med Ctr, Seoul, South Korea
[3] Dongguk Univ, Dept Obstet & Gynecol, Seoul, South Korea
[4] Konkuk Univ, Dept Immunol, Chungju, South Korea