1. Department of Obstetrics and Gynecology, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul 06236, Korea
2. The Institute of Reproductive Medicine and Population, Medical Research Center, Seoul National University College of Medicine, Seoul 03080, Korea
3. Department of Obstetrics and Gynecology, SMG-SNU Boramae Medical Center, Seoul 07061, Korea
4. Department of Obstetrics and Gynecology, Kyungpook National University School of Medicine, Daegu 41944, Korea
5. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul 03080, Korea