Growth tracks in early childhood M Hermanussen, S Lange and L Grasedyck University of Kiel, Germany Hermanussen M, Lange S, Grasedyck L. Growth tracks in early childhood. Acta Pædiatr 2001; 90: 381–386. Stockholm. ISSN 0803-5253 Aim: Child growth is modulated by numerous factors and, particularly in infancy and early childhood, often tends to follow apparently irregular patterns, 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 illnesses from four paediatric practices in Kiel, Germany. The children were measured 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 (range § 0.25) y. Each individual growth curve was converted into a series of height SDS (standard deviation scores) using one of the most reputable longitudinal German growth studies as background reference. Height SDS was then converted into residual height SDS (differences between height SDS of each measurement and average personal height SDS of the respective child). Cluster analysis was used to identify groups of children (clusters) with similarities in residual height SDS patterns (growth tracks). The clusters contained a minimum of at least 10 children. Single children or small sets of individuals below the minimum number were rejected from further analysis. Results: In males, 10 growth tracks were identied, each consisting of 11 to 52 boys. Growth in 111 boys was so heterogeneous that they could not be assigned to growth tracks. In females, 11 growth tracks were identied, each consisting of 12 to 48 girls; 112 girls could not be assigned. Approximately 7% of boys and 15% of girls showed evidence of a mild intermittent growth 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 declining growth in early infancy, or irregular patterns. Similar results were obtained when using cross-sectional standards as background reference. Conclusion: Cluster analysis provides evidence that the substantial diversity in infant and early child growth is limited to a small number of narrow but characteristic tracks of yet unknown biological signicance. Key words: Childhood growth, cluster analysis, growth pattern, growth tracks, ICP model, infant growth Michael Hermanussen, Aschauhof 3, DE-24340 Altenhof, Germany (Tel. ‡49 4351 41738, e-mail. hermanussen.aschauhof@t-online.de) Child growth is modulated by numerous factors, genetic and endocrine conditions, nutrition, illness (1), birth order (2), economic and environmental circumstances, social class (3), per capita income, number of children per family (4), and so on, which readily explains the diverseness of growth and the common difculties in predicting growth in the individual case. Particularly in infancy (5) and early childhood, when intrauterine and maternal inuences on growth disappear and non- maternal factors become dominant, child growth often tends to follow apparently irregular patterns, with many centiles crossed before the later growth channels are reached (6). In 1987, Karlberg and co-workers (7, 8) analysed longitudinal growth and suggested a mathematical model that divides the human growth process into three additive, partly superimposed phases—infancy, child- hood, and puberty (ICP-model). They observed that early growth velocity sharply declines during mid- infancy (Infancy component) and usually recovers before the end of the rst year of life. They used this phenomenon to identify the onset of a second distinct phase in human growth (Childhood component), and related their observations to endocrine phenomena. Intermittent short growth arrests and growth spurts are frequent in child development, and certainly do not exclusively reect endocrine factors, but changes in environmental conditions, feeding habits, intermittent illness and many other circumstances (9–11). Particu- larly at the end of infancy, the dramatic changes in Ó 2001 Taylor & Francis. ISSN 0803-5253 Acta Pñdiatr 90: 381±6. 2001