1. Department of Pediatrics; Okayama University Hospital; Okayama Japan
2. Department of Pediatrics; Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences; Okayama Japan
3. Department of Human Ecology; Okayama University Graduate School of Environmental and Life Science; Okayama Japan
4. Department of Pediatric Acute Medicine; Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences; Okayama Japan
5. Department of Epidemiology; Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences; Okayama Japan