Funding for this research was provided by:
Natural Science Foundation of Guangxi Province (2015GXNSFBA139129)
Guangxi Medical and Health Self-funding Project (No Z20170509 and No Z20180022)
the Liuzhou Science and Technology Bureau Project (No2017BD20201)
Received: 2 August 2018
Accepted: 31 October 2018
First Online: 12 November 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Liuzhou Maternity and Child Healthcare Hospital, and further permission was obtained from hospital to review the patient medical records.
: Not applicable.
: The authors declare that they have no competing interests.
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