Geographical differences in the effects of age and height at peak height velocity on final body height: An analysis of a population-based cross-sectional growth curve in Japan
Background. The aim of this study was to elucidate the effect of geographical differences in the age at peak height velocity (APHV) and height at peak height velocity (HPHV) on final height, at a prefectural level, and to evaluate the current average height status of 47 prefectures in Japan. Methods. We elucidated the association between the geographical differences in a prefectural-level cross-sectional population-based infancy-childhood-puberty (ICP) growth curve, derived from prefectural mean height data (age: 5-17 years, 2006-2013), APHV and HPHV, for final height. Results. The correlation between the APHV and final height was very weak; however, the results of a multiple regression analysis showed that the final height of each prefecture can be accurately predicted based on the APHV and HPHV. This result showed that the earlier the APHV and higher the HPHV, the higher the final height. An earlier APHV reduced the height gain in the puberty component; however, this did not reduce the final height. Discussion. From the perspective of the average value of each prefecture, in the present situation, the effect of an earlier APHV in increasing the amount of growth of the childhood component exceeded its effect in reducing the growth of the puberty component. In short, the final height of the prefectures depends on how large the height growth is in the early stages of childhood. However, the HPHV tended to be region-specific, and it is unlikely that it can increase the average height in this population in the future.