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

Aim To assess secular trend and changes in social inequalities of children's height across nearly 50 years, when vast socio-political changes took place in Poland. Methods Data on schoolchildren aged 7-18 years 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 withpost hocTukey's test and effect size calculations. Results 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. Conclusion Improvement of living conditions across nearly 50 years 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.

Automated summary

In Poland, there has been a positive secular trend in children's height over the past nearly 50 years. Socio-economic status has a significant impact on height, with differences in height between SES categories decreasing gradually over time. Despite improvements in living conditions, social inequalities still have biological effects on height differences in Poland.