Funding for this research was provided by:
national natural science foundation of china (No. 81372008)
Received: 24 June 2021
Accepted: 27 July 2021
First Online: 10 August 2021
: The study protocol was reviewed and approved by the Committee on Ethics and the institutional review board of Beijing Chao-Yang Hospital, Capital Medical University. It was confirmed that all methods were performed in accordance with the relevant guidelines and regulations in the “Methods” section, and a consent form was signed by parents of each child.
: Not applicable
: The authors declare that they have no competing interests.