1. Department of Epidemiology, College of Public Health, Shanxi Medical University, Taiyuan, China
2. Affiliated Cancer Hospital of Zhengzhou University, Henan Cancer Hospital, Zhengzhou, China
3. Department of Obstetrics, The First Affiliated Hospital, Shanxi Medical University, Taiyuan, China
4. Department of Information, The First Affiliated Hospital, Shanxi Medical University, Taiyuan, China
5. Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT, USA
6. Center for Disease Control and Prevention, Taiyuan Railway Administration, Taiyuan, China
7. Department of Surgery, Yale School of Medicine, New Haven, CT, USA