Article History
Received: 1 December 2021
Accepted: 25 February 2022
First Online: 3 April 2022
Declarations
:
: The authors declare that they have no conflicts of interest.
: This study was approved by the academic ethics committee of Hunan Province Maternal and Child Health care Hospital and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. All participants were fully informed and voluntarily signed the informed consent before sampling.
: Informed consent was obtained from all individual participants included in the study.