1. Department of Obstetrics and Gynecology, Tokai University School of Medicine, Isehara, Japan.
2. Department of Obstetrics and Gynecology, Kitasato University School of Medicine, Sagamihara, Japan.
3. Department of Obstetrics and Gynecology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
4. Department of Obstetrics and Gynecology, Kyorin University School of Medicine, Tokyo, Japan.
5. Department of Obstetrics and Gynecology, Kumamoto University, Faculty of Life Sciences, Kumamoto, Japan.