T Hata1,2, A Koyanagi1, T Yamanishi1, S Bouno1, R Takayoshi1, T Miyake1,2. 1. Department of Obstetrics and Gynecology, Miyake Clinic, Ohfuku, Minami-ku, Okayama, Japan. 2. Department of Perinatology and Gynecology, Kagawa University Graduate School of Medicine, Ikenobe, Miki, Kagawa, Japan.