Kong, Lijun http://orcid.org/0000-0002-1682-195X
Zhang, Chengyan
Article History
Received: 11 December 2019
Accepted: 25 July 2020
First Online: 5 August 2020
Ethics approval and consent to participate
: The present study was approved by the ethical review committee of Beijing Obstetrics and Gynecology Hospital, Capital Medical University. Written informed consent was obtained from all enrolled patients.
: Not applicable.
: The authors declare that they have no competing interests.