1. Midwifery Program, Kagawa Prefectural University of Health Sciences, Kagawa, Japan
2. Department of Nursing, Kansai University of Nursing and Health Sciences, Hyogo, Japan
3. Tsurugi-Handa Hospital, Tokushima, Japan
4. Department of Midwifery, Tokushima University Graduate School of Biomedical Sciences, Tokushima, Japan
5. Department of Health and Welfare System, College of Nursing Art and Science, University of Hyogo, Akashi, Japan
6. Department of Reproductive and Menopausal Medicine, Tokushima University Graduate School of Biomedical Sciences, Tokushima, Japan