Funding for this research was provided by:
Medical Science and Technology Research Project of Guangdong Province (A2016225)
Received: 16 December 2018
Accepted: 4 February 2019
First Online: 18 February 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: 201701085). 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.
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