Funding for this research was provided by:
National Natural Science Foundation of China (No. 81771657)
General Projects of Social Development in Shaanxi Province (No. 2018SF-260)
Article History
Received: 8 May 2019
Accepted: 31 October 2019
First Online: 9 November 2019
Compliance with ethical standards
:
: The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
: The approval of the Institutional Review Board of Northwest Women’s and Children’s Hospital was obtained for this retrospective cohort study (Number 2018002). All research was performed in accordance with relevant guidelines and regulations.
: Informed consent was obtained from all individual participants included in the study.