The Effect of the Second World War on the Growth Pattern of Height in Japanese Children: Catch-up Growth, Critical Windows and the First Thousand Days

This paper analyses the influence of the Second World War on the long-run pattern of child growth in Japan. We construct a prefecture-level dataset of mean heights of boys and girls from ages six to nineteen from 1929 to 2015. Linking the heights recorded at different ages for the same birth cohort, we measure a counterfactual causal effect of the nutritional shock of rationing, food shortages and other health shocks during the Second World War on the growth pattern of children. We find that at adulthood, Japanese boys and girls were 3.0 and 1.7 cm shorter than they would have been if the war had never occurred. The war also led to a delay in the pubertal growth spurt of about 0.5 years and slower maturation of children. These effects were greatest for children who experienced the war in late childhood and early adolescence. However, there were not strong penalties for children exposed to the war in utero and in early life, suggesting that they experienced catch-up growth as health conditions improved after the war. These findings challenge the thousand-days consensus that children cannot recover from nutritional shocks in early life and indicate that adolescence can be a sensitive period for health shocks.