Infant body mass index can predict obesity at age 2, study says

Weight-for-length measurements are not precise enough, said researchers in a recent study.

By Stephen Feller

PHILADELPHIA, April 22 (UPI) -- A high body mass index, or BMI, at two months old puts infants at increased risk for obesity by age 2, according to a recent study.

Researchers at the Children's Hospital of Philadelphia found BMI during infancy is a better predictor of later obesity than the standard weight-for-length measure employed during the first two years of life, according to a study published in the journal Pediatrics.


Before age two, doctors around the world are recommended to follow weight-for-length guidelines rather than BMI guides, which are used for children over age two to identify health problems. Weight-for-length guides do not correspond to age like BMI charts, however, which researchers said can make it difficult to determine if a child is obese.

"To our knowledge, this was the first study to compare BMI to WFL in predicting future obesity risk in a large, diverse cohort of full-term infants," Dr. Babette Zemel, director of the Nutrition and Growth Laboratory at Children's Hospital of Philadelphia, said in a press release. "We found that while BMI and WFL agreed after age six months, high BMI at age two months was a better predictor of obesity at two years of age than WFL. We recommend that clinicians consider measuring BMI in early infancy."


For the study, researchers analyzed medical records for 73,949 full-term infants' well-visits between 2006 and 2011 from birth until 24-months-old, finding BMI was more accurate before age two than WFL.

Of 2-month-old babies with a BMI above the 85th percentile, 31 percent were obese, compared to 23 percent of 2-month-olds at the 85th percentile on WFL charts, and 47 percent of children at the 97.7th percentile for BMI at 2 months old were obese by age 2, compared to 29 percent using WFL.

A wide range of potential causes for obesity have been identified in recent years -- from diet issues to genetics; however researchers in the new study say tools used to identify obesity may not be good enough because of the potential to stop the problem when it stops.

The researchers suggest adding BMI guidelines for children under age 2, based on the fast that measuring with BMI was a more reliable method for predicting obesity.

"An important factor in preventing obesity in adults is identifying at-risk individuals as early as possible, when interventions may have the greatest effect -- even during infancy," said Dr. Sani Roy, a pediatric endocrinology fellow at Children's Hospital of Philadelphia. "However, there is no currently accepted definition for excess body weight below age two."


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