In an 8 year Quebec Longitudinal Study of Child Development by Laura E. Pryor, MSc, and colleagues (from the National Institute of Health and Medical Research (INSERM) in Paris, France), to identify groups of children with distinct developmental trajectories of body mass index, it was found that children continuing on an elevated BMI trajectory leading to obesity in middle childhood can be distinguished from children on a normative BMI trajectory as early as age 3.5 years.

Three trajectories of BMI were identified in the study: low-stable (54.5% of children), moderate (41.0%), and high-rising (4.5%). The high-rising group was characterized by an increasing average BMI, which exceeded international cutoff values for obesity by age 8 years. Two maternal risk factors were associated with the high-rising group as compared with the low-stable and moderate groups combined: maternal BMI and maternal smoking during pregnancy.

The researchers calculated early weight gain as weight at 5 months minus weight at birth divided by 5 months. The study concludes that children continuing on an elevated BMI trajectory leading to obesity in middle childhood can be distinguished from children on a normative BMI trajectory as early as age 3.5 years and that important and preventable risk factors for childhood obesity are in place before birth.

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