1. Department of Obstetrics and Gynecology, Kansai Rosai Hospital, Amagasaki
2. Department of Biostatistics, Yamaguchi University Graduate School of Medicine, Yamaguchi
3. Department of Obstetrics and Gynecology, The Jikei University School of Medicine, Minato-ku
4. Department of Obstetrics and Gynecology, Kurume University School of Medicine, Fukuoka
5. Department of Obstetrics and Gynecology, Mie University, Graduate School of Medicine, Tsu
6. Department of Obstetrics and Gynecology, Hyogo College of Medicine, Nishinomiya
7. Department of Obstetrics and Gynecology, Nagoya City University West Medical Center, Nagoya
8. Department of Obstetrics and Gynecology, Iwate Medical University, Shiwa-gun
9. Department of Obstetrics and Gynecology, Tokyo Women’s Medical University Hospital, Shinjyuku-ku, Japan