Funding for this research was provided by:
Beijing Municipal Administration of Hospitals Clinical Medicine Development (ZYLX201830)
Beijing Hospitals Authority’ Ascent Plan (DFL20191401)
Received: 12 February 2020
Accepted: 29 June 2020
First Online: 20 July 2020
Ethics approval and consent to participate
: The study protocol was approved by the Ethics Committee of the Beijing Obstetrics and Gynecology Hospital, Capital Medical University.
: Not applicable.
: The authors declare that they have no conflict of interest.