1. Department of Obstetrics and Gynecology, University of Tokyo, Tokyo, Japan;
2. Department of Obstetrics and Gynecology, National Taiwan University Hospital, Hsin-Chu, Taiwan;
3. Department of Obstetrics and Gynecology, Kaoshiung Medical University Hospital, Kaohsiung, Taiwan;
4. Department of Obstetrics and Gynecology, School of Medicine, Kaoshiung Medical University, Kaohsiung, Taiwan