Not all children grow the same way. A new study from the Environmental influences on Child Health Outcomes (ECHO) Program suggests that body weight changes in early childhood may be associated with later obesity risk.
Funded by the National Institutes of Health (NIH), the study tracked children's body mass index (BMI) from infancy through age 9 and found two distinct growth patterns. Most children followed a typical curve, with BMI decreasing in early childhood before gradually rising again. But a smaller group followed a trajectory marked by a sharp rise in BMI, which put them at higher risk of developing obesity by age 9.
Key takeaways:
- Researchers found two main BMI growth patterns in children. Most children (89.4%) had a typical pattern where their BMI declined from ages 1 to 6, then rose slowly. A smaller group (10.6%) had an atypical pattern where their BMI stayed the same from ages 1 to 3.5, then increased rapidly from ages 3.5 to 9.
- By age 9, children in the atypical group were more likely to develop obesity, with an average BMI higher than the 99th percentile.
- Several early-life factors were associated with the child's risk of developing obesity, including high birthweight, maternal smoking during pregnancy, high maternal BMI before pregnancy, and excessive maternal weight gain during pregnancy.
Childhood obesity—defined as having a BMI at or above the 95th percentile for a child's age and sex—is often the result of excess body fat. Without support or intervention, children with higher BMI patterns in early life are more likely to carry that weight into adolescence and adulthood, increasing their chances of developing serious health conditions like diabetes and heart disease.
"The fact that we can identify unusual BMI patterns as early as age 3.5 shows how critical early childhood is for preventing obesity," said ECHO researcher Chang Liu, PhD, of Washington State University.
The study included 9,483 children across the United States who are part of the ECHO Cohort. Researchers looked at weight and height data collected over time from medical records, caregiver reports, and in-person or at-home measurements. They tracked how children's BMI changed as they grew and looked for patterns related to experiences early in life.
"Our findings suggest there are important opportunities to reduce childhood obesity, such as helping pregnant women quit smoking and manage healthy weight gain, as well as closely monitoring children who show early signs of rapid weight gain," said Liu.
This collaborative research is published in JAMA Network Ope n.
Liu, Chang, M., et al. (2025) Early-Life Factors and Body Mass Index Trajectories Among U.S. Children in the ECHO Cohort. JAMA Network Open. DOI:
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