1. Department of Obstetrics and Gynecology , Nagoya City University , Aichi , Japan
2. Department of Maternal and Fetal Medicine , Tohoku University Graduate School of Medicine, Miyagi Children’s Hospital , Miyagi , Japan
3. Department of Obstetrics and Gynecology , Showa University Northern Yokohama Hospital , Kanagawa , Japan
4. Department of Obstetrics and Gynecology , Nagoya City University West Medical Center , Aichi , Japan
5. Department of Obstetrics and Gynecology , Konan Kosei Hospital , Aichi , Japan
6. Department of Obstetrics and Gynecology , National Hospital Organization Saga Hospital , Saga , Japan
7. Clinical Research Management Center , Nagoya City University Hospital , Aichi , Japan
8. Department of Obstetrics and Gynecology , Tama-Nagayama Hospital, Nippon Medical School , Tokyo , Japan
9. Department of Obstetrics and Gynecology , Nagoya City University Graduate School of Medical Sciences , Aichi , Japan