Baby obesity: compare apples to apples.
Definition of childhood obesity needs a second look
In a March 30 article titled "Baby obesity: rapid infant weight gain linked to childhood obesity," Shelton of the Chicago Tribune reports on an interesting study relating birth weight, growth trajectories and obesity in toddlers. She reports the salient findings well, with a balanced perspective of interpretation, what further work is needed and why this study contributes novelty to our understanding of childhood growth trajectories.
The scientific study, by lead author Dr. Elsie Taveras and colleagues, compares the rate of weight gain in babies of the same birth weight and concludes that those who gain more weight during the same period of time are more likely to be obese as toddlers, explains Ms. Shelton.
The terms ‘baby obesity’ in the title and ‘obese by age 3’ in the lede sentence are apt to confuse readers, though. Typically, the Centers for Disease Control and Prevention (CDC) defines obese as infants and children that have a body mass index (BMI) at or above the 95th percentile of BMI in children of the same sex and age. In the research paper, Traveras used a different measurement -- called weight-for-length -- that measures body weight and length together.
However, Ms. Shelton didn't explain the CDC's measurement for childhood obesity and gave only a cursory mention of Taveras' measurement. The weight to length z scores also were referenced to BMI in adults rather than BMI in children.
From this apples to oranges comparison, readers may be left wondering what constitutes childhood obesity.
It would be helpful -- and a more accurate portrayal of the problem -- to have included a comparison of the weight-for-length measurement used by Taveras in the study to the CDC's BMI percentile-based obesity definition used for children.
