1. General Center for Perinatal, Maternal and Neonatal Medicine; Niigata University Medical and Dental Hospital; Niigata Japan
2. Department of Neonatology; Nagaoka Red Cross Hospital; Nagaoka Japan
3. Department of Neonatology; Uonuma Institute of Community Medicine; Niigata University Medical and Dental Hospital; Minamiuonuma Japan
4. Department of Pediatrics; Niigata University Graduate School of Medical and Dental Sciences; Niigata Japan