1. Department of Obstetrics and Gynecology, Japanese Red Cross Fukuoka Hospital, Ogusu, Minami-Ku, Fukuoka, Japan
2. Department of Obstetrics and Gynecology, Japanese Red Cross Matsuyama Hospital, Matsuyama, Ehime, Japan
3. Department of Pathology, Japanese Red Cross Fukuoka Hospital, Ogusu, Minami-Ku, Fukuoka, Japan