Funding for this research was provided by:
Maternal and Child Health Program of the National Health Commission of the People’s Republic of China (2015–42)
Article History
Received: 3 April 2023
Accepted: 11 July 2023
First Online: 17 August 2023
Declarations
:
: The study protocols of the NSPGDC were approved by the Ethics Committee of the Capital Institute of Pediatrics (SHERLL2015009). Informed consent was verbal and the ethics committee approved this procedure. Purpose, procedure, discomfort and benefit of the surveys were adequately explained by the staff of the cooperating groups to the parents, guardians and teachers involved in the survey. All the participants were voluntary.
: No financial or non-financial benefits have been received or will be received from any party related directly or indirectly to the subject of this article. The authors have no conflict of interest to declare.