Wang, Lijing http://orcid.org/0000-0002-1238-1918
Wang, Guanjun
Cao, Wenhong
Guo, Li
Hu, Haiyan
Li, Yuanmei
Zhang, Qian
Funding for this research was provided by:
the grants from Science and Technology Benefit People Special of Qingdao Science and Technology (19-6-1-56-nsh)
Article History
Received: 23 December 2019
Accepted: 6 May 2020
First Online: 2 July 2020
Compliance with ethical standards
:
: We have no conflicts of interest to declare.
: This study was approved by the institutional review board of Qingdao Municipal Hospital.
: Informed consent was signed by all pregnant women involved.