Funding for this research was provided by:
National Natural Science Foundation of China (8137027, 81501256)
Received: 21 June 2018
Accepted: 3 August 2018
First Online: 22 August 2018
Ethics approval and consent to participate
: This study has been approved by ethics boards of International Peace Maternity & Child Health Hospital. Patient provided written informed consents before taking invasive procedure.
: Informed consents can be supplied.
: The authors declare that they have no competing interests.
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