1. Department of Obstetrics & Gynaecology; Kangbuk Samsung Hospital; Sungkyunkwan University School of Medicine; Seoul Korea
2. Department of Obstetrics & Gynaecology; CHA Gangnam Medical Centre; CHA University; Seoul Korea
3. Department of Obstetrics & Gynaecology; Dongsan Hospital; Keimyung University School of Medicine; Daegu Korea