Zeng, Xiang-Dong http://orcid.org/0000-0002-4307-4777
Hu, Wen-Guang http://orcid.org/0000-0002-5620-7655
Article History
Received: 24 February 2020
Accepted: 2 July 2020
First Online: 6 July 2020
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: Informed consent was obtained from the parents or legal guardian of each child. The study was approved by the ethics committee of the Chengdu Women’s and Children’s Central Hospital.