1. Division of Public Health and Epidemiology, Department of Social Medicine Asahikawa Medical University Asahikawa Japan
2. Department of Obstetrics and Gynecology Asahikawa Medical University Asahikawa Japan
3. Division of Neonatology, Perinatal Medical Center Asahikawa Medical University Asahikawa Japan
4. Department of Pediatrics Asahikawa Medical University Asahikawa Japan
5. Faculty of Nursing Japanese Red Cross Hokkaido College of Nursing Kitami Japan
6. Center for Environmental and Health Sciences Hokkaido University Sapporo Japan
7. Faculty of Health Sciences Hokkaido University Asahikawa Japan