1. Obstetrical Gynecological Society of Osaka, Osaka, Japan
2. Department of Obstetrics and Gynecology, Osaka University Graduate School of Medicine, Osaka, Japan
3. Department of Obstetrics and Gynecology, Osaka Police Hospital, Osaka, Japan
4. Department of Obstetrics and Gynecology, Osaka Medical College Graduate School of Medical Sciences, Osaka, Japan
5. Department of Obstetrics and Gynecology, Osaka City University Graduate School of Medicine, Osaka, Japan
6. Department of Obstetrics and Gynecology, Kansai Medical University Graduate School of Medicine, Osaka, Japan
7. Department of Obstetrics and Gynecology, Kinki University Graduate School of Medical Sciences, Osaka, Japan
8. Department of Obstetrics and Gynecology, University of Occupational and Environmental Health Japan, Fukuoka, Japan
9. Department of Obstetrics and Gynecology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan