1. Department of Obstetrics and Gynecology, Guro Hospital, Korea University College of Medicine, Seoul, Korea.
2. Department of Obstetrics and Gynecology, School of Medicine, Kangwon National University, Chuncheon, Korea.
3. Department of Pathology, Guro Hospital, Korea University College of Medicine, Seoul, Korea.
4. Medical Science Research Center, Guro Hospital, Korea University College of Medicine, Seoul, Korea.