Received: 15 December 2020
Accepted: 7 June 2021
First Online: 7 July 2021
: The research was approved by the Ethics Committee of Shanghai Maternal and Child Health Center (2017-F001–04). All participants were informed about the study procedure and provided written informed consent. All methods were performed in accordance with the relevant guidelines and regulations (Declaration of Helsinki).
: No applicable.
: The authors declare that they have no competing interests.