Zhang, Ting
Wang, Huien
Wang, Xinling
Yang, Yue
Zhang, Yingkui
Tang, Zengjun
Wang, Li http://orcid.org/0000-0002-2940-5461
Funding for this research was provided by:
Department of Health of Hebei Province (18397779D)
Science and Technology Department of Hebei Province, China (2019YX013A)
Article History
Received: 24 October 2019
Accepted: 20 May 2020
First Online: 1 June 2020
Ethics approval and consent to participate
: Ethical clearance was approved by the institutional review board of Hebei Women and Children’s Health Center, and we had a permission to access the data used in our research of Hebei Women and Children’s Health Center on Oct-29, 2017 (No 20171029–1).
: It is not applicable.
: All authors declare that they have no competing interests.