Secular changes in the height of Polish schoolboys from 1955 to 1988

Abstract

Secular changes in height have been observed in many regions of Poland using cross-sectional data; however, data from four nationally representative surveys conducted from 1955 to 1988 have only been partially analyzed. Dramatic social and economic transitions during this 33 year period provide a unique opportunity to understand changes in growth within this historic context. We analyzed the changes in height of boys, aged 7-18 years, from surveys conducted in 1955, 1966, 1978 and 1988. Data for height were converted to Z-scores using the LMS method and the 2000 National Center for Health Statistics reference. In each consecutive survey year, boys at all ages were significantly taller than the same aged boys from the previous survey year, with mean height increases of a 2.35 cm, 3.43 cm and 1.47 cm between 1955 and 1966, 1966 and 1978 and 1978 and 1988, respectively. There were significant declines with age in height Z-scores from 7 to 14 years of age, followed by improvements relative to the reference between 14 and 18 years of age. The decline in Z-scores may be partially explained by an effect of delayed maturation. However, historic context also supports that some birth cohorts likely experienced a more adverse environment during early childhood than did other birth cohorts.

Figure 1. Difference in mean height (cm) between survey years at each age

Figure 2. Mean height Z-scores of Polish boys relative to the NCHS Z-score reference (zero line is the NCHS reference)

Figure 3. Mean height (cm) of boys at age 8 and 18 years, measured In the 1960's and the 1980's In different European countries

Figure 4. Historical framework for the growth of Polish school boys from the mid 1930s until the late 1980's