1. Department of Obstetrics and Gynecology, Daejeon St Mary’s Hospital, The Catholic University of Korea, Daejeon, South Korea
2. Department of Obstetrics and Gynecology, St Vincent’s Hospital, The Catholic University of Korea, Suwon, South Korea
3. Medical Science Research Institute, Kyung Hee University Medical Center, Kyung Hee University, Seoul, South Korea