Babies' BMI May Predict Childhood Obesity

A new study from The Children’s Hospital of Philadelphia shows body mass index (BMI) during infancy may help to predict if a child will be obese by age four. In work focused on the infant BMI-childhood obesity relationship in a cohort with a majority of African-American children, Children’s Hospital researchers say a better understanding of infant growth patterns may lead to more effective early efforts at obesity prevention.

“Given the public health importance of obesity-related medical problems, we investigated whether BMI in infants could be used as a tool to identify children at increased risk of future obesity, in order to develop better prevention strategies,” said the study’s leader, Shana E. McCormack, MD, a pediatric endocrinologist at CHOP. “We also analyzed ancestry-based differences in growth patterns, and found differences that were apparent at as early as nine months of age were ultimately related to childhood obesity risk.”

As a measure that includes both weight and height, BMI is an approximation of body fat content. BMI increases after birth, reaching its peak in infancy, usually between eight and nine months of age.

The current study, published in the Journal of Clinical Endicronology and Metabolism, analyzed the electronic health records of healthy Philadelphia-area infants, as part of a larger study conducted by the Center for Applied Genomics. Sixty-one percent of the children in the study were African-American, a population that has shown high rates of obesity and diabetes in adulthood. Investigators hope that more reliable, early identification of all infants at increased risk for obesity will offer a unique opportunity to develop and implement targeted interventions.

The research team identified significantly different growth trajectories between African-American infants and white infants. Peak infant BMI occurred around 12 days earlier in African-American children, and was about 3 percent higher in magnitude than others in the study, who were primarily of European ancestry. Overall, African-American infants appeared to have more than twice the risk of obesity at age four compared to infants of primarily European ancestry.

However, the study team performed statistical analyses to distinguish the effects of ancestry and infancy BMI, while also accounting for other factors such as birth weight and socioeconomic status. Their conclusion was that infancy BMI played a more important role than ancestry in determining the risk of childhood obesity. In addition, socioeconomic factors, inferred from geographic and insurance data, played a role in infancy BMI.

In children under age two, there is currently no consensus definition of obesity, said Dr. McCormack.

“In the absence of an accepted, valid definition of obesity in infancy, we struggle both as researchers and clinicians with how to best individualize recommendations for infants to prevent childhood obesity,” she added. “Our findings suggest that infant BMI pattern could be one additional tool. In addition, infant BMI may be an early metric to use in evaluating the impact of public policy interventions.”