Received: 11 June 2021
Accepted: 27 September 2021
First Online: 8 October 2021
: This study was approved by the Ethics Committee of The Fourth Hospital of Baotou, and the approval number from the Ethics Committee is not applicable.
: The guardians have given written consent for the publication of personal or clinical details of their child and any identifiable images in this study.
: The authors declare that they have no competing interests.