1. Department of Obstetrics and Gynecology, CHA Hospital Ilsan Medical Center, Goyang-si, South Korea
2. Dartmouth College, Hanover, NH
3. Department of Obstetrics and Gynecology, Chung-Ang University Hospital, Seoul, South Korea
4. Department of Obstetrics and Gynecology, Keimyung University School of Medicine, Daegu, South Korea
5. Department of Obstetrics and Gynecology, Sahmyook Medical Center, Seoul, South Korea
6. Department of Obstetrics and Gynecology, Dongguk University Ilsan Hospital, Goyang-si, South Korea
7. Department of Obstetrics and Gynecology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, South Korea