Secular change and socioeconomic difference in height in Japan

Abstract

The purpose of this review is to evaluate the anthropometric data taken by the author and her colleagues in the early 1990s, in which the subjects comprise both students and members of the general population who were born mostly in and after 1965. Secular changes and socioeconomic differences in height and some other major measurement items at age 20 in Japan are examined, using statistical reports from nationwide research conducted between 1892 and 1994. Socioeconomic difference in height at age 20 has disappeared in those born in the mid-1960s. The earlier maturing trend has stopped at the same time; however, adult height is still increasing slowly in those born in the 1960s, due to the increasing preadolescent growth rate. Possible causes of the secular change and the disappearance of socioeconomic difference in height are discussed in relation to changes in environmental factors. Secular changes in height at reference age (9 for boys, 7 for girls), height at age two, and postneonatal mortality suggest that secular change in height at age 20 may stop around 2005 more probably in females than in males. The estimated height at age 20 in 2003 is close to the mean height of the present subjects; thus the anthropometric data will be useful as reference data in ergonomic applications for at least two decades, even if the secular change continues at the present rate.