Iori Kisu1, Kouji Banno2, Yusuke Matoba2, Daisuke Aoki2. 1. Department of Obstetrics and Gynecology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan. iori71march@hotmail.co.jp. 2. Department of Obstetrics and Gynecology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.