1. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
2. Department of Obstetrics and Gynecology, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea.
3. The Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.
4. Department of Obstetrics and Gynecology, The Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.