1. Department of Obstetrics and Gynecology, Kurume University School of Medicine, Fukuoka, Japan.
2. Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, Japan.
3. Department of Reproductive Medicine, Graduate School of Medicine, Chiba University, Chiba, Japan.
4. Department of Obstetrics and Gynecology, School of Medicine, Dokkyo Medical University, Tochigi, Japan.
5. Department of Obstetrics and Gynecology, Tokai University School of Medicine, Kanagawa, Japan.
6. Department of Obstetrics and Gynecology, Tohoku University Graduate School of Medicine, Miyagi, Japan.
7. Department of Obstetrics and Gynecology, Niigata University School of Medicine, Niigata, Japan.