Article History
Received: 24 November 2017
Accepted: 25 June 2018
First Online: 11 July 2018
Ethics approval and consent to participate
: The study was approved by the Ethics Committees of Guangdong Women and Children Hosptial, and all participants provided written informed consent.
: Written informed consent was obtained from the patients.
: The authors declare that they have no competing interests.
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