Funding for this research was provided by:
the National Natural Science Foundation of China (81974217)
Major Scientific and Technological Projects for collaborative prevention and control of birth defects in Hunan Province (2019SK1015)
National Natural Science Foundation of China (81901388)
Received: 28 June 2020
Accepted: 21 January 2021
First Online: 1 February 2021
Ethics approval and consent to participate
: This study was conducted following the recommended guidelines prescribed by the Second Xiangya Hospital Ethics Committee. The parents of all participants signed consent prior to participation and were allowed to stop the participation without prejudice.
: Not applicable.
: The authors declare that they have no competing interests.