Lou, Didong http://orcid.org/0000-0003-0059-1587
Luo, Yan
Liu, Jing
Zheng, Dan
Ma, Rongrong
Chen, Fangping
Yu, Yanni
Guan, Zhizhong
Funding for this research was provided by:
Natural Science Foundation of China (81460483)
Article History
Received: 6 March 2020
Accepted: 24 April 2020
First Online: 3 May 2020
Compliance with Ethical Standards
:
: The authors declare that they have no conflict of interest.
: The study protocol was approved by the ethics committee of the Guizhou Medical University and Guiyang Maternal and Child Health Hospital.
: Informed consent was obtained from parents and respective school authorities.
: Not applicable.