Funding for this research was provided by:
National Natural Science Foundation of China (No. 81903335)
Received: 25 February 2021
Accepted: 18 March 2021
First Online: 30 March 2021
Change Date: 24 September 2021
Change Type: Correction
Change Details: A Correction to this paper has been published:
Change Details: https://doi.org/10.1186/S12884-021-04109-5
: Ethical approval for this study has been obtained from the Ethics Committee of Qingdao Women’s and Children’s Hospital (Number: 019–2019-FEKY). All participants sign a consent form prior to participating in the study.
: Not applicable.
: The authors declare that they have no competing interests.