1. National Center for Birth Defect Monitoring West China Second University Hospital Sichuan University Chengdu Sichuan China
2. Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University) Ministry of Education Chengdu Sichuan China
3. Department of Gynecology and Obstetrics Xichang People's Hospital Xichang China
4. Department of Gynecology and Obstetrics Rongchang Maternal and Child Care Hospital Chongqing China