1. Department of Orthopedics West China HospitalSichuan University Chengdu China
2. Department of Gynecology and Obstetrics West China Second University HospitalSichuan University Chengdu China
3. Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University)Ministry of Education Chengdu China
4. Department of Epidemiology and Health Statistics West China School of Public Health Sichuan University Chengdu China