[1] Mie Univ, Fac Med, Dept Obstet & Gynecol, 2-174 Edobashi, Tsu, Mie, Japan
[2] Sakakibara Heart Inst, Dept Obstet & Gynecol, Tokyo, Japan
[3] St Marianna Univ, Sch Med, Dept Obstet & Gynecol, Kawasaki, Kanagawa, Japan
[4] Toho Univ, Omori Med Ctr, Dept Obstet & Gynecol, Tokyo, Japan
[5] Seirei Hamamatsu Gen Hosp, Div Perinatol, Maternal & Perinatal Care Ctr, Hamamatsu, Shizuoka, Japan
[6] Showa Univ, Dept Obstet & Gynecol, Sch Med, Tokyo, Japan
[7] Hamamatsu Univ Sch Med, Dept Obstet & Gynecol, Hamamatsu, Shizuoka, Japan
[8] Ishiwata Obstet & Gynecol Hosp, Ibaraki, Japan