Received: 25 January 2021
Accepted: 2 July 2021
First Online: 16 July 2021
Change Date: 28 September 2021
Change Type: Correction
Change Details: A Correction to this paper has been published:
Change Details: https://doi.org/10.1186/S12884-021-04120-W
: This study was approved by the Institutional Review Boards of the Korea University Medical Center (2018GR0401). This committee granted an exemption from requiring informed consent. The study was performed in accordance with the declaration of Helsinki.
: Not applicable.
: The authors report no conflict of interest.