2000 CDC Growth Charts: Features and Data

Overview

The data used to create the 2000 CDC Growth Charts included a nationally representative reference population of children and adolescents from 1963 to 1994. CDC used statistical smoothing methods to create smooth curves from this data. Read more about statistical smoothing or the LMS (lambda-mu-sigma) parameters for the 2000 growth charts.

Key features

The 2000 CDC Growth Charts for children and adolescents aged 2 to 20 years include:

• BMI-for-age charts.
• Stature-for-age and weight-for-age charts.
• Smoothed percentile curves and corresponding z-scores to help plot and track growth. These are often the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles.

Growth reference population

The data used to construct the 2000 CDC Growth Charts were nationally representative and obtained from five national survey datasets. The measurement data came from surveys that the National Center for Health Statistics conducted from 1963 to 1994. These surveys included:

• National Health Examination Survey (NHES), Cycle II (1963 to 1965; aged 6 to 11 years).
• NHES, Cycle III (1966 to 1970; aged 12 to 17 years).
• National Health and Nutrition Examination Survey (NHANES) I (1971 to 1974; aged 2 to 20 years).
• NHANES II (1976 to 1980; aged 2 to 20 years).
• NHANES III (1988 to 1994; aged 2 to 20 for stature and aged 2 to 5 years for weight and BMI).

Each cross-sectional survey included a national probability sample of the civilian, noninstitutionalized U.S. population. Researchers applied survey-specific sample weights to the survey sample data to ensure U.S. population representation for age, sex, and racial or ethnic composition.

Data exclusions

NHANES III (1988 to 1994) weight data for children 6 years and older were excluded. This is because an upward shift in the weight-for-age and BMI-for-age curves occurred in the 1980s and 1990s. There was an increase in obesity prevalence among children 6 and older in NHANES III data compared to previous data. If data from NHANES III had been included, the resulting 95th percentile curve would have been higher. This would have classified fewer children and adolescents as having obesity.

Test your knowledge

1. The 2000 CDC Growth Charts include weight-for-age charts, stature-for-age charts, and BMI-for-age charts for children 2 to 20 years.
   1. True
   2. False
2. Why were weights of children aged 6 and older from the NHANES III survey excluded from the growth reference data when developing the 2000 CDC Growth Charts?
   1. Measurement errors in NHANES III make the data invalid.
   2. The smaller sample size of older children in NHANES III made the curves statistically unreliable.
   3. There was a decrease in obesity prevalence among children aged 6 and older. This would change the growth reference.
   4. There was an increase in obesity prevalence among children aged 6 and older in NHANES III data compared to previous data. This would have moved the growth reference higher and resulted in classifying fewer children and adolescent as having obesity.

See answers.A