Chen, Zhonglan
Li, Youping
Chen, Juan
Guo, Xiujing
Article History
Received: 28 July 2021
Accepted: 31 December 2021
First Online: 8 March 2022
Declarations
:
: The ethics committee of West China Second University Hospital of Sichuan University approved the study protocol (No. 2019 (002)). The procedures used in this study adhered to the principles of the Declaration of Helsinki. All pregnant women signed informed consent forms before participation.
: Not applicable
: The authors declare that they have no competing interests.