1. Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine
2. Perinatal Center, Division of Maternal and Fetal Medicine, Jichi Medical University, Saitama Medical Center
3. Departments of Obstetrics and Gynecology, Jichi Medical University School of Medicine
4. Department of Obstetrics and Gynecology, Faculty of Medicine, The University of Tokyo
5. Center for Maternal, Fetal and Neonatal Medicine, Saitama Medical Center, Saitama Medical University