1. Department of Obstetrics and Gynecology, Tokyo Medical and Dental University School of Medicine, Tokyo, Japan.
2. Saga Nutraceuticals Research Institute, Otsuka Pharmaceutical Co., Ltd, Saga, Japan.
3. Faculty of Health Care, Kiryu University, Gunnma, Japan.
4. Taguchi Obstetrics and Gynecology Clinic, Saitama, Japan.
5. Department of Obstetrics and Gynecology, Kyushu Central Hospital, Fukuoka, Japan.
6. Department of Obstetrics and Gynecology, Tokyo Dental College, Ichikawa General Hospital, Chiba, Japan.
7. Department of Obstetrics and Gynecology, St. Marianna University School of Medicine, Kanagawa, Japan.
8. Department of Obstetrics and Gynecology, Hirosaki University School of Medicine, Aomori, Japan.
9. Department of Obstetrics and Gynecology, Tokyo Women's Medical University, Tokyo, Japan.