Measuring body mass index (BMI) during infancy may help to predict if a child will be obese by age four, says a study.

The findings suggest that understanding of infant growth patterns may lead to more effective early efforts at obesity prevention.

As a measure that includes both weight and height, BMI is an approximation of body fat content.

"We also analysed ancestry-based differences in growth patterns and found differences that were apparent as early as nine months of age were ultimately related to childhood obesity risk," said study leader Shana McCormack, pediatric endocrinologist at the Children’s Hospital of Philadelphia (CHOP).

The current study analysed the electronic health records of 2,114 healthy infants in Philadelphia.

"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," McCormack noted.

The current study analysed 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.

The research team identified significantly different growth trajectories between African-American infants and infants of European ancestry.

Peak infant BMI occurred around 12 days earlier in African-American children, and was about three percent higher in magnitude than others in the study, who were primarily of European ancestry.

BMI increases after birth, reaching its peak in infancy, usually between eight and nine months of age, the study pointed out.

Overall, African-American infants appeared to have more than twice the risk of obesity at age four compared to infants of primarily European ancestry.

The study appeared in the Journal of Clinical Endocrinology and Metabolism.