[1] Tokyo Womens Med Univ, Dept Neonatol, 8-1 Kawadacho,Shinjuku Ku, Tokyo, Japan
[2] Natl Ctr Child Hlth & Dev, Dept Hlth Policy, 2-10-1 Ookura,Setagaya Ku, Tokyo, Japan
[3] Kyorin Univ, Dept Pediat, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan
[4] Neonatal Res Network Japan, 3-7-1 Nishishinjuku,Shinjuku Ku, Tokyo, Japan
[5] Kyoto Univ, Grad Sch Med, Yoshidakonoecho,Sakyo Ku, Kyoto, Japan
[6] Kanagawa Childrens Hosp, Dept Neonatol, 2-138-4 Mutsugawa,Minami Ku, Yokohama, Kanagawa, Japan
[7] Shizuoka Grad Univ Publ Hlth, 4-27-2 Kita Ando, Aoi, Shizuoka, Japan
[8] Juntendo Univ, Sch Med, Dept Publ Hlth, 2-1-1 Hongo,Bunkyo Ku, Tokyo, Japan
[9] Jichi Med Univ, Dept Pediat, 3311-1 Yakushiji, Shimotsuke, Tochigi, Japan
[10] Tokai Univ, Dept Pediat, 143 Shimokasuya, Isehara, Kanagawa, Japan
[11] Osaka Womens & Childrens Hosp, Dept Neonatol, 840 Murodocho,Izumi Ku, Osaka, Japan