Funding for this research was provided by:
Fujian Maternity and Child Health Hospital (YCXB 18-10 and YCXM 19-04)
Article History
Received: 24 March 2020
Accepted: 25 June 2020
First Online: 8 July 2020
Compliance with ethical standards
:
: The authors declare that they have no conflicts of interest.
: Not applicable.
: Not applicable.