Growth tracks in early childhood

Aim: Child growth is modulated by numerous factors and, particularly in inf ancy and early childhood, often tends to follow apparently irregular patter ns, with many centiles crossed before the later growth channels are reached . The aim of this study was to visualize the diversity of individual growth , Design: The study investigated 333 girls and 329 boys without chronic ill nesses from four paediatric practices in Kiel, Germany. The children were m easured on natural, i.e., on various occasions, when they were presented to their doctors for preventive care examinations and for minor illnesses, at the age of 0.25 (range +/- 0.08) y, 0.5 (range +/- 0.16) y, 0.75 (range +/ - 0.16) y, 1.0 (range +/- 0.25) y, and at the ages of 1.5, 2, 3, 4 and 5 (r ange +/- 0.25) y. Each individual growth curve was converted into a series of height SDS (standard deviation scores) using one of the most reputable l ongitudinal German growth studies as background reference, Height SDS was t hen converted into residual height SDS (differences between height SDS of e ach measurement and average personal height SDS of the respective child). C luster analysis was used to identify groups of children (clusters) with sim ilarities in residual height SDS patterns (growth tracks). The clusters con tained a minimum of at least 10 children. Single children or small sets of individuals below the minimum number were rejected from further analysis. R esults. In males, 10 growth tracks were identified, each consisting of 11 t o 52 boys. Growth in 111 boys was so heterogeneous that they could not be a ssigned to growth tracks. In females, 11 growth tracks were identified, eac h consisting of 12 to 48 girls; 112 girls could not be assigned. Approximat ely 7% of boys and 15% of girls showed evidence of a mild intermittent grow th spurt at the end of infancy. Some growth tracks were almost horizontal, or showed declining residual height SDS up to the age of 3 and 4 y, with no evidence of growth spurts during early childhood. Others showed sharply de clining growth in early infancy, or irregular patterns. Similar results wer e obtained when using cross-sectional standards as background reference. Conclusion: Cluster analysis provides evidence that the substantial diversi ty in infant and early child growth is limited to a small number of narrow but characteristic tracks of yet unknown biological significance.