Describing the children's body shape by means of Geometric Morphometric techniques

Abstract

Introduction: Large shape variations take place during the growth process of children, including quantitative mass and size increase plus qualitative changes in their body shape. The aim of the present study is to apply Geometric Morphometric techniques in order to visualize and quantify such body shape differences in healthy children aged 6–59 months with optimal nutritional status. Materials and methods: Anthropometrical measurements of weight, height, and middle-upper arm circumference were used to assess nutritional status on a sample of 258 Senegalese (n = 154) and Spanish (n = 104) children. A set of 36 anatomical and/or osteologically-based landmarks were identified on the body of the children along with 108 semi-landmarks used to capture curvature attributes on the frontal view of the body image. A specific method was developed to place and photograph children, as well as to locate landmarks, treat images and calculate semi-landmarks. Shape differences among children were analyzed in terms of age, sex, and population origin, taking into consideration allometry effects. Results: Our results indicate significant differences in shape and size for all the three factors under study before removing size effect (p <.0001), and in shape after the size correction (p <.01). Only the ontogenetic effect persisted in the size of studied individuals after size-effects correction (p <.0001). Morphometric significant differences were described regarding age for PC1 and population origin in PC2 before removing size effect. Between-population morphometric differences were sorted along PC1 after size correction. Discussion: Geometric Morphometric techniques are useful to study morphometric changes in the anterior whole-body view of children under 5 years old, allowing a precise description of shape changes observed when age and population origin are considered.