1. Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, CHA University, Seoul, Korea.
2. Department of Obstetrics and Gynecology, CHA Bundang Medical Center, CHA University, Seongnam, Korea.
3. Department of Obstetrics and Gynecology, Samsung Medical Center, Seoul, Korea.
4. Department of Obstetrics and Gynecology, Ajou University School of Medicine, Suwon, Korea.
5. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea.
6. Department of Internal Medicine, Institute of Health and Environment, Seoul National University, Seoul, Korea.
7. Department of Obstetrics and Gynecology, MizMedi Hospital, Seoul, Korea.