Funding for this research was provided by:
Shenzhen Health and Family Planning Commission (SZBC201801)
Shenzhen Science and Technology Innovation Committee (JCYJ20160429102107498)
Shenzhen Medical Sanming Project (SZSM201612045)
Received: 25 November 2018
Accepted: 18 April 2019
First Online: 30 April 2019
Ethics approval and consent to participate
: The Shenzhen Maternity and Child Health Care Hospital Institutional Ethical Committee approved the collection and usage of the clinical information for research purposes before the investigation was initiated and waived the requirement for informed consent (IEC No. -082).
: Not applicable.
: The authors declare that they have no competing interests.
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