Funding for this research was provided by:
Shenzhen Science and Technology Innovation Committee (JCY20160425152812445)
Received: 13 February 2019
Accepted: 12 August 2019
First Online: 19 August 2019
Ethics approval and consent to participate
: This study had been approved by the Medical Ethics Committee of Shenzhen Nanshan Maternity and Child Healthcare Hospital, Shenzhen, the People’s Republic of China, and written informed consent was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.