Funding for this research was provided by:
Chongqing Municipal Commission of Health and Family Planning (2015MSXM112)
Received: 26 October 2020
Accepted: 22 March 2021
First Online: 31 March 2021
: Ethical approval for the study, including the permission to access and use the datasets, was obtained from the Institutional Review Board of Chongqing University Three Gorges Hospital and University-Town Hospital of Chongqing Medical University.
: Not applicable.
: The authors declare that they have no competing interests.