Funding for this research was provided by:
Science and Technology Commission of Shanghai Municipality (19ZR1450900)
Shanghai Municipal Health and Family Planning Commission Fund (20174Y0054)
Text and Data Mining valid from 2020-01-21
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.