1. I-one Center, Seoul Women's Hospital, Bucheon, Korea.
2. Department of Obstetrics and Gynecology, Medical Research Center, Seoul National University College of Medicine, 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, Wonju Severance Christian Hospital, Yonsei University Wonju College of Medicine, Wonju, Korea.