Funding for this research was provided by:
Birth Defect Control and Prevention Project of Shaanxi Commission of Health and Family Planning (No. Sxwsjswzfcght2016-013)
National Natural Science Foundation of China (No. 81230016)
Received: 11 November 2020
Accepted: 28 September 2021
First Online: 6 October 2021
: The research was performed in accordance with the Declaration of Helsinki and approved by the Human Research Ethics Committee of Xi’an Jiaotong University Health Science Center (No.2012008). All participants gave informed written consent to participate in the study.
: Not applicable.
: The authors declare that they have no competing interests.