Rapid increase in Japanese life expectancy after World War II.

Japanese life expectancy increased by about 13.7 years during the first decade after World War II, despite the country's post-war poverty. Although it is known that medical progress explains part of this increase, roles of non-medical factors have not been systematically studied. This study hypothesizes that non-medical factors, in addition to medical factors, are associated with the rapid increase in life expectancy in Japan. We analyzed the time trends of potential explanatory factors and used regression analysis with historical data from the Ministry of Internal Affairs and Communications' Historical Statistics of Japan during the period between 1946 and 1983. Time trends analysis revealed that the rapid increase in life expectancy preceded the dramatic growth of per capita Gross Domestic Product (GDP) by 10 years. In education, the nearly universal enrollment in elementary schools and increased advancement to upper secondary schools for both sexes were associated with better health. Regarding legislation, 32 health laws were passed in the first decade after the war and these laws were associated with improved health. Using regression analysis, we found that the enrollment rate in elementary schools, the number of health laws, and expansion of community-based activity staff were significantly associated with the increased life expectancy during the first decade after World War II. To conclude, in addition to medical factors, non-medical factors applied across the country, particularly education, community-based activities and legislation were associated with the rapid increase in Japanese life expectancy after World War II.