1. Department of Obstetrics and Gynecology West China Second University Hospital of Sichuan University the Key Laboratory of Birth Defects and Related Diseases of Women and Children Sichuan University Ministry of Education Chengdu Sichuan China
2. West China School of Medicine Sichuan University Chengdu Sichuan China
3. Department of Medical Record West China Second University Hospital Sichuan University Chengdu Sichuan China