Body mass index during infancy might help predict whether a child will be obese by age 4, according to a large study by researchers with The Children’s Hospital of Philadelphia. Better understanding of infant growth patterns might lead to more effective early efforts at obesity prevention, the researchers said in a news release.
Results from the study, which tracked a cohort with a majority of African-American children, were published Jan. 30 on the website of the Journal of Clinical Endocrinology & Metabolism.
“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,” study leader Shana E. McCormack, MD, a pediatric endocrinologist at CHOP, said in the release. “We also analyzed ancestry-based differences in growth patterns, and found differences that were apparent at as early as 9 months of age were ultimately related to childhood obesity risk.”
BMI increases after birth, reaching its peak in infancy, usually between 8 and 9 months of age. Researchers analyzed the electronic health records of 2,114 healthy Philadelphia-area infants, as part of a larger study conducted by CHOP’s Center for Applied Genomics. Sixty-one percent of the children in the study cohort were African-American, a population that, according to national estimates, has high rates of obesity and diabetes in adulthood.
Investigators hope more reliable, early identification of all infants at increased risk for obesity will offer a unique opportunity to develop and implement targeted interventions.
Findings showed significantly different growth trajectories between African-American infants and white infants. Peak infant BMI occurred about 12 days earlier in African-American children and was about 3% higher in magnitude than others in the study, who were primarily of European ancestry.
Overall, the study found African-American infants appeared to have more than twice the risk of obesity at age 4 compared with 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 infancy BMI played a more important role than ancestry in determining the risk of childhood obesity. They also found socioeconomic factors — inferred from geographic and insurance data — played a role in infancy BMI. Higher rates of poverty, for instance, were associated with higher and earlier peak BMI.
The study provides rich longitudinal data, including drawing on the many measurements that are made routinely during infancy and early childhood at well-child check-ups, first author Sani M. Roy, MD, a pediatric endocrinology fellow at CHOP, said in the release.
The actual causes of these differences in infancy BMI and risk of childhood obesity in African-Americans remain subjects for further research. One study co-author, Babette S. Zemel, PhD, the director of the Nutrition and Growth Laboratory at CHOP, is leading a prospective study of African-American infants and families, investigating factors such as hormone levels, variations in intestinal bacteria and feeding practices such as breast-feeding and formula feeding on growth and excess weight gain.
In children under age 2, there is no consensus definition of obesity, McCormack said in the release.
“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 said in the release. “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.”
This study was supported by the National Institutes of Health.
Study abstract: http://doi.org/10.1210/jc.2014-4028