Funding for this research was provided by:
Medical Science and Technology Research Project of Guangdong Province (A2019358, A 2018212)
Text and Data Mining valid from 2019-11-29
Received: 2 April 2019
Accepted: 7 November 2019
First Online: 29 November 2019
Ethics approval and consent to participate
: The study has been approved by the Institutional Review Board/ Medical Ethics Committee of Guangdong Women and Children Hospital (IRB reference number: 201711085). Written informed consent was obtained from all participants, their parents or legal guardians (in the case of children under 16).
: Not applicable.
: The authors declare that they have no competing interests.