1. Department of Obstetrics and Gynecology Ajou University School of Medicine Suwon South Korea
2. Department of Obstetrics and Gynecology, CHA Bundang Medical Center CHA University School of Medicine Seongnam South Korea
3. Department of Obstetrics and Gynecology, CHA Gangnam Medical Center CHA University School of Medicine Seoul South Korea
4. Department of Obstetrics and Gynecology, University of Ulsan College of Medicine Asan Medical Center Seoul South Korea