[1] Osaka Med Ctr, Dept Maternal Fetal Med, 840 Murodocho, Izumi, Osaka 5941101, Japan
[2] Res Inst Maternal & Child Hlth, 840 Murodocho, Izumi, Osaka 5941101, Japan
[3] Natl Ctr Child Hlth & Dev, Ctr Maternal Fetal Neonatal & Reproduct Med, Tokyo, Japan
[4] Jikei Univ, Sch Med, Dept Obstet & Gynecol, Tokyo, Japan
[5] Showa Univ, Dept Obstet & Gynecol, Tokyo, Japan
[6] Kyorin Univ, Dept Obstet & Gynecol, Tokyo, Japan
[7] Toho Univ, Fac Med, Dept Med Stat, Yokohama, Kanagawa, Japan
[8] Kanagawa Childrens Med Ctr, Dept Obstet, Yokohama, Kanagawa, Japan
[9] Hyogo Prefectural Kobe Childrens Hosp, Dept Obstet, Kobe, Hyogo, Japan
[10] Seirei Hamamatsu Gen Hosp, Maternal & Perinatal Care Ctr, Hamamatsu, Shizuoka, Japan
[11] Miyagi Childrens Hosp, Dept Obstet, Sendai, Miyagi, Japan