1. Department of Obstetrics and Gynecology, Kosin University College of Medicine, Busan, Korea.
2. Department of Obstetrics and Gynecology, Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea.
3. Department of Obstetrics and Gynecology, Gyeongsang National University School of Medicine, Jinju, Korea.
4. Department of Obstetrics and Gynecology, Konkuk University School of Medicine, Seoul, Korea.