Funding for this research was provided by:
Project of Guangzhou Science and Technology,China (No. 201510010173)
Project of Science and Technology of Guangdong Province Government,China (No. 2017ZC0317)
Received: 10 January 2018
Accepted: 1 October 2018
First Online: 29 November 2018
Ethics approval and consent to participate
: This study was approved by Guangdong Women and Children Hospital Ethics Committee(reference number: 201701005). And all participants provided written informed consent before specimens collection, according to institutional guidelines in this research.
: Not applicable.
: The authors declare that they have no competing interests.
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