Received: 22 May 2020
Accepted: 2 July 2020
First Online: 7 July 2020
Ethics approval and consent to participate
: Informed consent was waived by the Institutional Review Board of Tokyo Women’s Medical University, approval number 4416, July 11, 2017, due to the retrospective nature of the study.
: Not applicable
: The authors declare that they have no competing interests.