1. Department of Obstetrics and Gynecology, National Health Insurance Ilsan Hospital, Goyang, Korea.
2. Department of Obstetrics and Gynecology, Seoul National University Hospital, Seoul, Korea.
3. Department of Obstetrics, Gynecology, and Women’s Health, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
4. Department of Obstetrics and Gynecology, CHA Bunding Medical Center, CHA University School of Medicine, Seongnam, Korea.
5. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.