Secular growth changes in Zagreb schoolchildren over four decades, 1951-91

Secular changes in growth and development vary over past decades in intensity and in trend. The purpose of this paper is to present changes in growth patterns of Zagreb schoolchildren aged 7-19 years over the past four decades. Surveys were performed in 1951, 1964, 1973, 1982 and 1991. The mean height of boys and girls in all observed groups has increased significantly over the 40-year period. Age groups up to 9 years in 1991 were 4-7.5 cm taller than their coevals in 1951. Differences increased from the age of 10 in girls and 12 in boys, reaching 10 cm in girls of 12 years and even 14 cm in boys of 14 years. They were also highly pronounced in adult height (5 cm in girls, 7 cm in boys). The most pronounced changes appeared from 1951 to 1964, while in the period from 1964 to 1973 the increase was smaller; in girls only up to 13 years, in boys to 17 years. However, between 1973 and 1982 positive changes were again significantly pronounced, especially in the older age groups. In the last period, 1982-91, the trend seemed to come to an end. Changes in average weight mostly corresponded to the height changes, being somewhat greater in boys. Moreover, in the last two periods, weight gain in older girls was smaller compared to height. Menarche in the period 1964-73 shifted to a younger age by 8 months (13.34-12.67 years), retaining the same level over the next 9 years. However, since 1982 a slight reverse trend has been noticed.