Developmental Trajectories of Body Mass Index in Early Childhood

Laura Pryor, B.Sc, B. SW
Evelyne Touchette, PhD, Christophe Genolini, PhD, Richard E. Tremblay, PhD,
Dubois, Lise, PhD, Bruno Falissard, MD, PhD, Sylvana M. Côté, PhD

Contexte :
Childhood obesity has become one of the greatest Public Health challenges this century, affecting not only developed nations, but increasingly low- and middle-income countries as well. Estimating developmental trajectories of Body Mass Index (BMI) during early childhood represents an innovative approach towards a better understanding of the development of this health problem. Objective: To identify groups of children with distinct developmental trajectories of Body Mass Index (BMI) between the ages of five months and eight years, and to identify early-life risk factors that distinguish children in an atypically elevated BMI trajectory group.

Méthode :
Group-based developmental trajectories of BMI were estimated from annual maternal assessments (5 months to 8 years) in a large population sample (n=1957). Measures of height and weight, as well as family and child characteristics were obtained yearly from mothers. Multivariate logistic regression was used to distinguish children with elevated BMI from other children, using pre and early post-natal risk factors.

Résultats :
Three trajectories of BMI were identified: low-stable BMI (54.5%), moderate BMI (41.0%) and high-rising BMI (4.5%). The high-rising group included children whose BMI, at eight years of age, exceeded the cut-off value for obesity. Multinomial logit regression analyses revealed that two maternal risk factors were significantly associated with the high-rising BMI trajectory group as compared to both the low and moderate groups: smoking during pregnancy and maternal overweight.

Conclusion :
Antecedents of childhood obesity can be identified during pregnancy. Intervention studies are needed in order to test the possibility that targeting maternal smoking and maternal obesity during pregnancy would reduce the risk of childhood obesity in the offspring.