Received: 16 March 2018
Accepted: 30 April 2019
First Online: 14 May 2019
Ethics approval and consent to participate
: This study has been performed in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Zhuhai Municipal Maternal and Children’s Health Hospital. Written informed consents from all patients were obtained prior to the study.
: Not applicable.
: The authors declare that they have no competing interests.
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