[1] Yamaguchi Univ, Perinatal Care Ctr, Ube, Yamaguchi 7558505, Japan
[2] Seirei Hamamatsu Gen Hosp, Maternal & Perinatal Care Ctr, Hamamatsu, Shizuoka, Japan
[3] Japan Fetoscopy Grp, Tokyo, Japan
[4] Niigata Univ, Grad Sch Med & Dent Sci, Dept Obstet & Gynecol, Niigata, Japan
[5] Nagara Med Ctr, Dept Fetal Maternal Med, Gifu, Japan