Funding for this research was provided by:
key discipline project of Tianjin health and family planning commission (13KG125)
Text and Data Mining valid from 2019-01-29
Received: 15 August 2018
Accepted: 3 January 2019
First Online: 29 January 2019
Ethics approval and consent to participate
: The study protocol was approved by the Ethic Committee of the Tianjin Children’s Hospital and conducted in accordance with Helsinki’s Declaration. Consent to participate from the under 16 years old was given by a legal guardian.
: Not applicable.
: The authors declare that they have no competing interest.
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