1. Department of Obstetrics and Gynecology, St Marianna University School of Medicine, Kanagawa, Japan;
2. Center for Maternal-Fetal, Neonatal and Reproductive Medicine, The National Center for Child Health and Development, Tokyo, Japan;
3. Department of Obstetrics and Gynecology, Kansai Medical University, Osaka, Japan;
4. Department of Obstetrics and Gynecology, Showa University School of Medicine, Tokyo, Japan;
5. Department of Clinical Genetics, Yokohama City University Hospital, Kanagawa, Japan;
6. Department of Obstetrics and Gynecology, Sanno Birth Center, Tokyo, Japan;
7. Department of Maternal and Fetal Medicine, Tohoku University Graduate School of Medicine, Miyagi Children’s Hospital, Miyagi, Japan;
8. Department of Obstetrics and Gynecology, Kochi Health Sciences Center, Kochi, Japan;
9. Department of Obstetrics and Gynecology, Okayama Medical Center, National Hospital Organization, Okayama, Japan;
10. Department of Obstetrics and Gynecology, Yamanashi Prefectural Central Hospital, Yamanashi, Japan;
11. Department of Obstetrics and Gynecology, Juntendo University Urayasu Hospital, Chiba, Japan;
12. Department of Obstetrics and Gynecology, Kawasaki Medical School Hospital, Okayama, Japan;
13. Department of Obstetrics and Gynecology, Ehime University School of Medicine, Ehime, Japan;
14. Department of Obstetrics and Gynecology, Toho University Omori Medical Center, Tokyo, Japan;
15. Perinatal Medical Center, Medical Genetics Center, Shikoku Medical Center for Children and Adults, Kagawa, Japan;
16. Department of Obstetrics and Gynecology, Saitama Medical University Hospital, Saitama, Japan