Funding for this research was provided by:
Research Project of the Health and Family Planning Commission of Yibin
Article History
Received: 2 October 2019
Accepted: 9 November 2019
First Online: 3 December 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.