Funding for this research was provided by:
Young Scientists Fund (81901929)
Research project of Health and Family Planning Commission Of Sichuan Province (17PJ136)
Research project of Zigong City Science & Technology and Intellectual Property Right Bureau (2017SF04, 2018SF04)
Received: 26 July 2020
Accepted: 3 October 2020
First Online: 8 October 2020
Ethics approval and consent to participate
: This study was an analysis of the third-party anonymized databases with pre-existing IRB approval.
: Not applicable.
: The authors declare that they have no competing interests.