Funding for this research was provided by:
The Scientific research project of Sichuan provincial health and Family Planning Commission (18PJ115)
The National Nature Science Foundation of China (81860469)
Received: 23 February 2020
Accepted: 23 June 2020
First Online: 10 July 2020
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Sichuan Provincial People’s Hospital (NO.2019–323).
: Not applicable.
: The authors declare that they have no competing interests.