Funding for this research was provided by:
Beijing Municipal Commission of Health and Family Planning (2018-2-4067)
Received: 7 January 2019
Accepted: 16 September 2019
First Online: 27 November 2019
Ethics approval and consent to participate
: The Ethics Committee of the China–Japanese Friendship Hospital approved this study on 16 May 2018 (2018–57-K41). Written informed consent was obtained from all volunteers, and the study conformed to the ethics principles set forth by the Declaration of Helsinki.The study has been approved by the Ethics Research Committees of the China–Japan Friendship Hospital with identifier 2018–57-K41–1. Any revisions of the study protocol will be submitted to the ethics committee.
: Not applicable.
: The authors declare that they have no competing interests.