Secular Trend of Height Variations in Iranian Population Born between 1940 and 1984

Abstract

Background: Iran, a low- to middle-income country, has experienced considerable socioeconomic changes in 20^th century, which their impacts on the adult heights has not been assessed deeply by now. This article aims to quantify the temporal varia­tions of height (with respect to shrinkage of height due to aging) and its deterministic factors in Iranian population born be­tween 1940 and 1984.

Methods: We analyzed the data of a large-scale national population- based survey that recruited 89,532 healthy subjects aged from 15 to 64 in 2005. Having used the Baltimore Longitudinal Study of Aging formulae, the shrinkage of height due to aging was adjusted. We modeled the estimated maximum height using multivariate regression analysis based on year of birth, sex, residing area and literacy. Moreover, we generated series of country maps showing the average of height classi­fied by decades and provinces.

Results: On average, the height of Iranian population has increased around 1.28 cm per decade (1.17cm in females; 1.53cm in males). The most prominent jumps of male and female heights are observed in 1970s. However, the jump of height in women has occurred around 3.5-10 years later than in men.

Conclusion: We found a very sharp and clear increasing trend in height among those who were born between 1940 and 1984. Our findings support the fact that the socio-economical variations have had considerable impact on the maximum height of people; this can prove the population height measure as a good historical determinant for socio-economical de­velop­ment trend.