How to Interpret CDC Growth Charts
Use CDC growth charts for children aged 24 months through 20 years, applying the 5th and 95th percentiles as cutoffs for identifying children who need further evaluation for growth abnormalities. 1
Age-Based Chart Selection
The CDC provides clear guidance on which growth standards to use based on age:
- Children < 24 months: Use WHO growth charts (not CDC charts) 1
- Children 24 months to 20 years: Use CDC growth charts 1
This age-based approach exists because the WHO charts reflect optimal growth patterns of predominantly breastfed infants, while CDC charts better represent the diverse U.S. population after age 2 years and provide continuity through adolescence 1.
Key Percentile Cutoffs for CDC Charts
For children ≥24 months using CDC charts, apply these thresholds:
- ≤5th percentile: Indicates potential growth concern (underweight, short stature, or low weight-for-stature depending on parameter measured) 1
- ≥95th percentile: Indicates potential overweight/obesity concern 1
These percentiles identify approximately 10% of the reference population at the extremes, flagging children who warrant clinical evaluation 1.
Parameters to Plot
Track these growth measurements on CDC charts:
- Weight-for-age: Assesses overall body mass relative to age
- Length/stature-for-age: Evaluates linear growth
- Weight-for-stature: Identifies disproportionate weight gain or loss
- BMI-for-age: Primary tool for assessing overweight/obesity in children ≥2 years 2, 3
Critical Interpretation Pitfalls
Formula-fed vs. breastfed infants near the transition age (18-24 months): Formula-fed infants tend to gain weight more rapidly after 3 months and may cross upward in percentiles, potentially being classified as overweight 1. This represents a normal feeding pattern difference, not necessarily pathology, though early recognition of obesity trends may trigger appropriate interventions 1.
The 24-month transition point: When switching from WHO to CDC charts at age 24 months, expect an apparent drop in BMI and weight z-scores even in children with stable growth patterns 4. Recent evidence shows mean BMI z-score decreases of -0.59 and weight z-score decreases of -0.35 when using the abrupt CDC-recommended transition, with 28.3% of children showing a large drop in BMI z-score 4. Recognize this as an artifact of chart transition, not true growth faltering.
Clinical Action Based on Percentiles
When measurements fall ≤5th percentile: Investigate for underlying causes including inadequate nutrition, chronic disease, neglect, or genetic conditions 1. Children identified at this threshold are more likely to have substantial deficiencies requiring immediate attention 1.
When measurements fall ≥95th percentile: Evaluate for excessive weight gain and consider interventions to modify growth trajectory, particularly for BMI-for-age 1.
Serial measurements matter more than single points: Growth velocity and pattern over time provide more clinically meaningful information than isolated percentile values. A child consistently tracking along the 10th percentile may be healthy, while a child crossing multiple percentile lines downward warrants investigation regardless of absolute percentile 5.
Accessing the Charts
CDC growth charts are available at https://www.cdc.gov/growthcharts, including training tools for clinicians 1.