The aim of the study was to investigate the individual variability in growth tracking from birth to the end of growth of children born in 1990 in Vilnius city and region and to investigate its sexual differences.
Materials and methods. The analysis of 1490 personal health records of children born in 1990 in Vilnius city and region (760 boys and 730 girls) was performed. The data on children’s weight and height from birth up to the age of eighteen years were collected. The frequency in the shifts in the main percentiles for height and weight were assessed every year and every month of the first year. The main growth percentiles (3, 10, 25, 50, 75, 90 and 97) were computed from the cross-sectional data of morphological and physical status of Lithuanian children [12]. We investigated changes in growth tracking (up and down) of child’s height and weight during various periods of age. Child’s growth was considered stable, if growth indices did not change or changed only one percentile channel (growth track); unstable - if two and more percentile channels were changed during the investigated period of time.
Results. The most unstable growth was observed during the first and the second year of life. Almost half of investigated children’s height (45.2% boys and 45.8% girls) and weight (43.95% boys and 37.4% girls) changed two and more growth tracks during the first year of life. During the second year unstable height growth was recorded in more than one-third (37.7% boys and 36.3% girls), and weight - in one-fifth of children (20.86% boys and 20.09% girls).As children grew, growth tracks were changed less often, and from the beginning of school age the stable growth in height has been recorded in more than 90% children of both sexes. Weight gain stabilization was observed from the tenth year until the end of growth, when the stable increase in weight of more than 95% children of both sexes was recorded. The boys changed the growth tracks for height more frequently than the girls during fifth, sixteenth, seventeenth and eighteenth year of life, the girls - during twelfth year of life (p<0.05). The boys changed the growth tracks for weight more frequently than the girls during first, fourth and seventh, the girls - during ninth year of life (p<0.05). Weight was more stable growth index than height.
Conclusions. The individual variability in growth tracking of height and weight seems to be the normal phenomenon. The greatest variability in growth tracking of height and weight was recorded during the first and second years of life. Stabilization in growth tracking of height and weight was observed during the growth process.
Keywords: growth of children, longitudinal study, growth tracking, shifts in percentiles, growth stabilization.
