1. Division of Neonatology, Maternal and Perinatal Center; Toyama University Hospital; Toyama Japan
2. Toyama Prefectural Central Hospital; Toyama Japan
3. Koseiren Takaoka Hospital; Toyama Japan
4. Toyama City Medical Association; Toyama Japan
5. Department of Public Health, Faculty of Medicine; University of Toyama; Toyama Japan
6. Department of Pediatrics, Faculty of Medicine; University of Toyama; Toyama Japan