^○Hiroya Itagaki¹, Masato Nishida², Yuko Nagai², Miyako Sakanaka², Ryota Ichikawa², Yuko Arai², Toyomi Satoh¹ (1.Department of Obstetrics and Gynecology, Faculty of Medicine, University of Tsukuba, Japan, 2.Department of Obstetrics and Gynecology, National Hospital Organization, Kasumigaura Medical Center, Japan)

^○Chih-Feng Yen^1,2 (1.Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Linko branch, Taoyuan, 2.Chang Gung University, Taiwan)

^○Hong Xu (Department of Gynecology and Obstetrics, International Peace Maternity and Child Health Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China)

^○Yasushi Kotani, Kosuke Murakami, Naho Sasai, Yoko Kashima, Hanako Sato, Mamiko Ohta, Kaori Moriuchi, Kiko Yamamoto, Chiho Miyagawa, Masato Aoki, Yoshie Yo, Akiko Kanto, Hisamitsu Takaya, Kaoru Kawasaki, Hidekatsu Nakai, Noriomi Matsumura (Department of Obstetrics and Gynecology, Kindai University Faculty of Medicine, Osaka, Japan)

^○Yong Wook Jung (Department of Obstetrics and Gynecology, CHA Universtiy, Seoul, Korea)