Funding for this research was provided by:
Shanghai Municipal Health and Family Planning Commission Fund (20174Y0054)
Shanghai Science and Technology Committee (19ZR1450900)
Received: 10 October 2019
Accepted: 7 January 2020
First Online: 21 January 2020
Ethics approval and consent to participate
: This study was approved by the institutional review board of our hospital, and the requirement for informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.