Funding for this research was provided by:
National Natural Science Foundation of China (31970798)
National Natural Science Foundation of China (81373868)
National Natural Science Foundation of China (31671200)
National Natural Science Foundation of China (91542108)
National Natural Science Foundation of China (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.