1. Department of Obstetrics and Gynecology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
2. Research Institute for National Cancer Control & Evaluation, National Cancer Center, Seoul, Korea.
3. Department of Obstetrics and Gynecology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Korea.
4. Department of Obstetrics and Gynecology, St. Vincent's Hospital, The Catholic University of Korea, Suwon, Korea.
5. Department of Obstetrics and Gynecology, Chonnam National University Medical School, Gwangju, Korea.
6. Department of Laboratory Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
7. Department of Obstetrics and Gynecology, Keimyung University School of Medicine, Daegu, Korea.
8. Noncommunicable Diseases and Health Promotion, World Health Organization, Western Pacific Regional Office, Manila, the Philippines.