Received: 16 November 2021
Accepted: 26 August 2022
First Online: 3 September 2022
: This study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethnic Committee of the Ningbo Women and Children’s Hospital(approval number: EC2017-003). All data were collected from the electronic medical record system in the department of Obstetrics Medicine Center. Data were anonymized and de-identified before analysis.
: Not applicable.
: The authors declare no conflict of interest.