Funding for this research was provided by:
Guangdong Science and Technology Department (2014A020212246, 2016A020218011)
Guangzhou Science, Technology and Innovation Commission (201904010452)
Text and Data Mining valid from 2020-04-07
Received: 16 November 2019
Accepted: 25 March 2020
First Online: 7 April 2020
Ethics approval and consent to participate
: This study was approved by the ethics committee of the Guangdong Women and Children Hospital (ref. 201901117). All clinical data used in this study were anonymized prior to analysis, and the requirement for written informed consent was waived.
: Not applicable.
: The authors declare that they have no competing interests.