1. Department of Fetal-Maternal Medicine; Nagara Medical Center; Gifu Japan
2. Department of Obstetrics and Gynecology; Hyogo College of Medicine; Nishinomiya Japan
3. Department of Obstetrics; Miyagi Children's Hospital; Sendai Japan
4. Department of Obstetrics and Gynecology; Elm Josei Clinic; Aomori Japan
5. Department of Obstetrics and Gynecology; Hokkaido University; Sapporo Japan
6. Department of Obstetrics and Gynecology; Aichi Children's Health and Medical Center; Aichi Japan
7. Department of Obstetrics and Gynecology; Kurume University School of Medicine; Fukuoka Japan
8. Department of Obstetrics and Gynecology; Yamaguchi Grand Medical Center; Yamaguchi Japan
9. Division of Clinical Genetics; Nippon Medical School Hospital; Tokyo Japan
10. Department of Radiology; National Center for Child Health and Development; Tokyo Japan
11. Department of Radiology; Tokyo Metropolitan Kiyose Children's Hospital; Tokyo Japan