Change of growth acceleration in Japan as indicated by the maximum growth age in height and sitting height

Abstract

From the trend of maximum growth age (MGA) of height (MGA-h) and sitting height (MGA-sh) in both Okinawa Prefecture and Aomori Prefecture, we projected the trend of national readings:1) The transition of MGA-h and MGA-sh first appears in younger ages in less populated areas such as in Okinawa and Aomori. Later the transition toward the younger age begins nationally.2) The national girls'MGA-h will emerge at the age of 9, because this trend has already appeared in both Okinawa and Aomori.3) The girls'MGA-sh will be hereafter shifted to 10 years of age nationally. Only one time has the national MGA-sh actually been seen at the age of 10. This occurred in 1983. However it has been seen a few times in Okinawa and Aomori prefectures.4) For boys, the current national MGA-h and MGA-sh is reached at 12 years of age. The boys'MGA-h and MGA-sh has not been seen to lower to the 11-year age group in Okinawa and Aomori prefectures. Hypothetically the national MGA-h and MGA-sh will stay constant at 12 years of age for a while.5) The growth acceleration of MGA has shown the following pattern: the current age group will stay constant over the course of a few years; then it alternately interchanges with the group one year younger for a period of time; the younger group will then maintain its position as the new age of MGA.