Funding for this research was provided by:
Health and Family Planning Commission of Sichuan Province (No. 16PJ067)
Received: 5 November 2021
Accepted: 10 May 2022
First Online: 19 July 2022
: We confirm that all methods were carried out in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. We confirm that written informed consent has been obtained from all participants from their parents and/or legal guardians.The study was approved by the ethics committees of Chengdu Women’s and Children’s Central Hospital (Ethnic audit number 2016 [CitationRef removed]).
: Not applicable.
: The authors declare that they have no competing interests.