1. Department of Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Dankook University School of Medicine, Seoul, Korea.
2. Department of Obstetrics and Gynecology, Ilsin Christian Hospital, Busan, Korea.
3. Department of Obstetrics and Gynecology, Miz Women's Hospital, Daejeon, Korea.
4. Department of Obstetrics and Gynecology, Mam's Women's Hospital, Ulsan, Korea.
5. Department of Obstetrics and Gynecology, Catholic University of Daegu School of Medicine,
Daegu, Korea.
6. Department of Obstetrics and Gynecology, Chonnam National University Medical School, Gwangju, Korea.