1. Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea
2. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea
3. Jaewang Lee is now with Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
4. Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul, Korea