1. I-one Center, Seoul Women's Hospital, Bucheon, Korea.
2. Department of Obstetrics and Gynecology, Pusan National University School of Medicine and Medical Research Institute, Pusan National University Hospital, Busan, Korea.
3. Department of Obstetrics and Gynecology, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.
4. The Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea.