Affiliation: | 1. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Institute of Women's Life Medical Science, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea;2. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Konkuk University College of Medicine, Seoul, Korea;3. Department of Biostatistics, Yonsei University College of Medicine, Seoul, Korea |