Hiroaki Itoh1, Atsuo Itakura2, Naohiro Kanayama1, Tomoaki Ikeda3. 1. Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Japan. 2. Department of Obstetrics and Gynecology, Faculty of Medicine, Juntendo University, Tokyo, Japan. 3. Department of Obstetrics and Gynecology, Mie University, Tsu, Japan.