1. Department of Obstetrics and Gynecology, St. Marianna University School of Medicine, Kanagawa, Japan
2. Department of Obstetrics and Gynecology, Mie University School of Medicine, Mie, Japan
3. Department of Obstetrics and Gynecology, Miyazaki University, Faculty of Medicine, Miyazaki, Japan
4. Department of Obstetrics and Gynecology, Showa University School of Medicine, Tokyo, Japan
5. Ishiwata Obstetrics and Gynecology Hospital, Ibaraki, Japan