1. Department of Obstetrics and Gynecology, Showa University School of Medicine
2. Department of Obstetrics and Gynecology, Mie University School of Medicine
3. Department of Obstetrics and Gynecology, Toho University School of Medicine
4. Division of Perinatology, Maternal and Perinatal Care Center, Seirei Hamamatsu General Hospital
5. Department of Obstetrics and Gynecology, Sakakibara Heart Institute
6. Ishiwata Obstetrics and Gynecology Hospital
7. Seijo-Kinoshita Hospital