[1] Univ Tokyo, Grad Sch Med, Dept Pediat, 7-3-1 Hongo Bunkyo Ku, Tokyo, Japan
[2] Tokyo Womens Med Univ Hosp, Dept Neonatol, Tokyo, Japan
[3] Tama Nagayama Hosp, Nippon Med Sch, Dept Obstet & Gynecol, Tokyo, Japan
[4] Univ Alabama Birmingham, Heersink Sch Med, Dept Pediat, Div Neonatol, Birmingham, AL USA
[5] Osaka Womens & Childrens Hosp, Dept Neonatal Med, Izumi, Japan
[6] Saitama Med Univ, Saitama Med Ctr, Dept Pediat, Kawagoe, Japan
[7] Natl Ctr Child Hlth & Dev, Div Neonatol, Tokyo, Japan
[8] Kanagawa Childrens Med Ctr, Dept Neonatol, Yokohama, Japan