Text and Data Mining valid from 2018-07-11
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.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.