1. Gynecology and obstetrics of West China 2nd University Hospital, Key Laboratory of Birth Defects and Related Diseases of women and Children, Ministry of Education, 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. Neonatal Department of West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
4. Nursing Department of West China Second University Hospital, Sichuan University, Chengdu, Sichuan, China
5. West China School of Nursing, Sichuan University, Chengdu, Sichuan, China