Funding for this research was provided by:
Shanghai Municipal Health Bureau (201840149)
Received: 16 September 2020
Accepted: 3 June 2021
First Online: 29 June 2021
: This retrospective, observational cohort study was approved by the Ethics Committee of Shanghai First Maternity and Infant Hospital, Shanghai, China (Ethics No.: KS1990, October 20, 2019). Due to the nature of the study, the requirement for written informed consent was waived. The study followed the Strengthening the Reporting of Observational Studies in Epidemiology statement.
: Not applicable.
: The authors report no conflicts of interest.