Funding for this research was provided by:
Young Scientists Fund (81702212)
Received: 6 September 2020
Accepted: 29 March 2021
First Online: 2 April 2021
: This retrospective study was approved by the Ethics Committee of The Second Hospital of Shanxi Medical University. The written informed consent was obtained from their parents for the study.
: The written informed consent for publication was obtained from their parents.
: The authors declare that they have no conflict of interests related to this work.