1. Department of Obstetrics and Gynecology, Kumamoto University Faculty of Life Sciences, Kumamoto, Japan.
2. Department of Obstetrics and Gynecology, Japanese Red Cross Kumamoto Hospital, Kumamoto, Japan.
3. Department of Obstetrics and Gynecology, Kumamoto Rosai Hospital, Yatsushiro, Japan.
4. Department of Obstetrics and Gynecology, Arao Municipal Hospital, Arao, Japan.
5. Department of Obstetrics and Gynecology, National Hospital Organization Kumamoto Medical Center, Kumamoto, Japan.
6. School & Graduate School of Health Sciences, Kumamoto University Faculty of Life Sciences, Kumamoto, Japan.