BMI May Predict Infant’s Risk for Obesity in Early Childhood

Mother and infant
Mother and infant
Infants in the 85th percentile for BMI are at increased risk for obesity by age 6.

BOSTON — Infants who are above the 85th percentile for weight are more likely to become severely obese by age 6.

Allison R. Smego, MD, a clinical fellow for the division of endocrinology at Cincinnati Children’s Hospital Medical Center, said BMI trajectories for severely obese children begin differing from normal-weight children as early as 4 months of age, 12 to 18 months before the median onset of clinical obesity

“At 6, 12, or 18 months of age, a BMI greater than or equal to the 85th percentile on the World Health Organization (WHO) BMI growth charts led to a greater than 50% chance of being overweight or obese by age 6 years,” she said. “Having a BMI exceeding the 85th percentile during infancy leads to a 3- to 9-fold increased risk of developing severe obesity by age 6.”

Dr Smego presented the data at ENDO 2016.

She and her colleagues hoped to characterize growth patterns of children who become severely obese (BMI >99th percentile) by age 6 to identify whether these children had a critical period of deviation from normal growth, and to characterize that growth relative to normally-developing children.

The researchers evaluated 2 lean cohorts (BMI from the 5th percentile to 75th percentile), 1 from a low-income primary care clinic (n=647) and another from a longitudinal epidemiologic study (n=136). Two severely obese cohorts, 1 from a low-income primary care clinic (n=365) and 1 from an obesity referral clinic (n=115), were selected based on BMI between ages 2 and 6.

Sex distribution of patients was similar among all groups.

Onset of clinical obesity occurred at median of 2.00 years of age in the low-income obese group and at 1.36 years in the obesity clinic group. However, BMI differed significantly between the severely obese and lean cohorts by 4 months of age (P<.0001) while WHO weight-for-age percentile differed by 2 months (P<.0001).

BMI high-specificity thresholds (95%) accurately differentiated severely obese patients from leaner counterparts at 6 (51%), 12 (52%), and 18 months of age (95%).

“BMI percentile should be assessed in children from 6 months onward to identify those at high risk of later onset obesity,” Dr Smego said.


  1. Smego A, Woo JG, Klein J, et al. OR07-5: BMI Trajectory of Severely Obese Children Diverges from Normal-Weight Children during Infancy. Presented at: ENDO 2016; April 1-4, 2016; Boston, MA.