1. Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Department of Obstetrics and Gynecology
2. Hiroshima Prefectural Hospital, Division of Reproductive Medicine
3. Hiroshima University Hospital, Department of Obstetrics and Gynecology
4. Department of Epidemiology, Infectious Disease Control and Prevention, Graduate school of Biomedical and Health Sciences, Hiroshima University