1. Department of Obstetrics and Gynecology, Institute of Women's Life Medical Science, Yonsei University College of Medicine, Seoul, Korea.
2. Institute of Health and Environment, Seoul National University Graduate School of Public Health, Seoul, Korea.
3. Department of Health Policy and Management, Seoul National University Graduate School of Public Health, Seoul, Korea.
4. Korean Health Promotion Foundation, Seoul, Korea.
5. Department of Obstetrics and Gynecology, Seoul National University Bundang Hospital, Seongnam, Korea.
6. Department of Obstetrics and Gynecology, Seoul National University College of Medicine, Seoul, Korea.
7. Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea.
8. Department of Family Medicine, Seoul National University College of Medicine, Seoul, Korea.