1. Department of Health Policy, National Center for Child Health and Development, 10‐1, Okura 2 chome, Setagaya, Tokyo 157‐8535 Japan
2. Division of Health Policy Development and Research, (takehara‐k@ncchd.go.jp), Department of Health Policy, National Center for Child Health and Development, 10‐1, Okura 2 chome, Setagaya, Tokyo 157‐8535 Japan
3. Department of Social Medicine, National Center for Child Health and Development, 10‐1, Okura 2 chome, Setagaya, Tokyo 157‐8535 Japan
4. Department of Empirical Social Security Research, National Institute of Population and Social Security Research, 2‐2‐3, Uchisaiwaicyo, Chiyoda‐ku, Tokyo 100‐0011 Japan
5. Global Health Nursing, Graduate school of nursing science, St. Luke's international University, 10‐1, Akashicho, Chuo‐ku, Tokyo 104‐0044 Japan
6. Health Policy for Children and Families, Graduate School of Medicine, Kyoto University, Yoshida‐Konoe‐cho, Sakyo‐ku, Kyoto 606‐8501 Japan