1. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Obstetrics and Gynecology, Cheil General Hospital and Women's Healthcare Center, Dankook University College of Medicine, Seoul, Korea.
3. Department of Obstetrics and Gynecology, CHA Gangnam Medical Center, CHA University School of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Internal Medicine, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.
6. Department of Obstetrics and Gynecology, Seoul Metropolitan Government-Seoul National University Boramae Medical Center, Seoul, Korea.