[1] St Marianna Univ, Grad Sch Med, Dept Perinatal Dev Pathophysiol, 2-16-1Sugao,Miyamae Ku, Kawasaki, Kanagawa 2168511, Japan
[2] Showa Univ, Sch Med, Dept Obstet & Gynecol, Tokyo, Japan
[3] Kumamoto Gen Hosp, Dept Obstet & Gynecol, Kumamoto, Japan
[4] Miyazaki Univ, Sch Med, Dept Obstet & Gynaecol, Miyazaki, Japan
[5] Toho Univ, Fac Med, Dept Obstet & Gynecol, Tokyo, Japan
[6] Seirei Hamamatsu Gen Hosp, Maternal & Perinatal Care Ctr, Div Perinatol, Hamamatsu, Japan
[7] Ishiwata Obstet & Gynecol Hosp, Ibaraki, Japan
[8] Mie Univ, Sch Med, Dept Obstet & Gynecol, Tsu, Mie, Japan