Secular trend and social variation in height of Polish schoolchildren between 1966 and 2012

Abstract

To assess secular trend and changes in social inequalities of children's height across nearly 50years, when vast socio-political changes took place in Poland. Data on schoolchildren aged 7-18years were collected in 1966, 1978, 1988 and 2012 in Poland. Height was standardised for age using the LMS method. Socio-economic status (SES) was based on 4 factors: urbanisation level, mother's and father's education, and family size (number of children). Statistics included 2-way ANOVA with post hoc Tukey's test and effect size calculations. Positive secular trend in height was observed across all years. All analysed SES factors had significant effect on height which differed depending on SES category and year of Survey. Differences in height between extreme categories of SES factors decreased gradually, starting from 1978. However, only general SES in girls and urbanisation level in both sexes became insignificant in 2012. Improvement of living conditions across nearly 50years was reflected in the secular trend in children's height. Despite this improvement, however, the biological effects of social inequalities, visible in differences in height, to some extent, are still present in Poland.