1 Department of Neonatology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
2 Center for Clinical Epidemiology and Evidence-Based Medicine, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
3 Department of Otorhinolaryngology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.
4 Key Laboratory of Major Diseases in Children, Ministry of Education, Beijing 100045, China.