1. 1: Japan Ministry of Internal Affairs and Communications, Statistics Bureau: http://www.stat.go.jp/english/data/handbook/ c02cont.htm#cha2_2).
2. 1: Japan Ministry of Internal Affairs and Communications, Statistics Bureau: http://www.stat.go.jp/english/data/handbook/ c02cont.htm#cha2_2).
3. 2: Ministry of Health labour and Welfare of Japan, Outline of Vital Statistics: www.mhlw.go.jp/english/database/db-hw/outline/index.html.
4. 2: Ministry of Health labour and Welfare of Japan, Outline of Vital Statistics: www.mhlw.go.jp/english/database/db-hw/outline/index.html.
5. 3: Loke AY, Poon CF (2011): The health concerns and behaviours of primigravida: comparing advanced age pregnant women with their younger counterparts. J Clin Nurs, 20: 1141-1150.