Funding for this research was provided by:
Japan Society for the Promotion of Science
Mitsui Sumitomo Insurance Welfare Foundation
Received: 10 April 2017
Accepted: 3 October 2017
First Online: 16 October 2017
: ST is an assistant professor of maternal nursing and researcher, and SH is a professor of midwifery and researcher.
: This study was approved by the institutional review board at St. Luke’s International University, Tokyo, Japan (no. 14–001). Informed consent to participate in this study was obtained from all participants.
: Not applicable.
: The authors declare that they have no competing interests.
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