1. Department of Pediatrics, National Center for Global Health and Medicine Hospital, 1-21-1 Toyama, Shinjuku-ku, Tokyo 162-8655, Japan
2. Department of Pediatrics and Child Health, Nihon University School of Medicine, 30-1 Oyaguchikami-cho, Itabashi-ku, Tokyo 173-8610, Japan
3. Division of Neonatology, Nagano Children’s Hospital, 3100 Toyoshina, Azumino-shi, Nagano 399-8288, Japan