Height increase was observed in urban areas but not in rural areas for births from 1885 to 1912 in Iwate, Japan

Previous studies have reported that height reduction due to urbanization during the early industrial period was not observed in Japan. This study analyzed the data from 20-year- old conscript examinations from 1905 to 1932 (for individuals born between 1885 and 1912) in Iwate Prefecture, northern Japan. Secular trends in height, weight, body mass index (BMI), prevalence of trachoma, and secondary education attainment classified by Morioka City, the prefectural capital, and 13 counties were examined. Before the 1880s births, the height of those in Morioka was approximately 159 cm, the same height as those in rural areas. After 1880, the height of those in Morioka increased to more than 161 cm in the early 1900s, while the height of those in rural areas remained constant. Large declines in height, > 0.5 cm, were seen in those born in the year or following year of a natural disaster, epidemic, or economic depression. This result may suggest that height increased in urban areas as life improved, experiencing temporary deterioration of their living environment due to recession, natural disasters, and epidemics, whereas height changed little in rural areas because life remained almost the same during the early industrial period in Japan.