Article History
Received: 13 July 2019
Accepted: 17 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: This study was approved by the Ethics Committee of Women and Children’s Hospital, School of Medicine, Xiamen University.Informed consent was waived since it was a retrospective study and the data used were deidentified.
: Not applicable.
: The authors declare that they have no competing interests.