1. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea
2. Department of Obstetrics and Gynecology, Yonsei University Graduate School, Seoul, Korea
3. Institute of Women's Life Medical Science, Department of Obstetrics and Gynecology, Yonsei University College of Medicine, Seoul, Korea
4. Department of Biochemistry and Molecular Biology, Yonsei University College of Medicine, Seoul, Korea
5. Department of Pathology, Yonsei University College of Medicine, Seoul, Korea