Funding for this research was provided by:
National Natural Science Foundation of China (31970798, 81373868, 31671200, 91542108, 81471513)
Article History
Received: 6 December 2019
Accepted: 13 April 2020
First Online: 12 May 2020
Ethics approval and consent to participate
: The study protocol was approved by the Human Ethics Committee of the Fudan University Obstetrics and Gynecology Hospital (Ethics 2018–70).
: All authors agree to publish.
: The authors declare that there is no potential conflict of interest.