Funding for this research was provided by:
the Public Welfare Research Special Fund of the National Health and Family Planning of China (No. 201402007.)
Article History
Accepted: 13 March 2021
First Online: 19 April 2021
Declarations
:
: The authors declare that they have no conflicts of interest.
: This article does not contain any studies with animals performed by any of the authors.
: This study was approved by the Capital Institute of Pediatrics hospital’s ethical board (SHERLL2013064).
: The individual written informed consent was waived because of the retrospective design.