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The 2000 CDC Growth Charts: Features and Data

The data used to create the 2000 CDC Growth Charts included a nationally representative reference population of children and teens aged 2 to 20 years during 1963–94. Statistical smoothing methods were used to fit the data from national surveys to create smooth curves. Read more about statistical smoothing procedures [PDF-5.3MB] or the LMS (lambda-mu-sigma) parameters [PDF-87KB] for the 2000 growth charts.

Key Features of the 2000 CDC Growth Charts

What is a z-score?

A z-score is a statistical measure indicating how far a given measure is from the mean (or average). Z-scores have direct relationships with percentiles; for every z-score there is a corresponding percentile.

  • BMI-for-age charts for children and teens aged 2 to 20 years.
  • Stature-for-age and weight-for-age charts for children and teens aged 2 to 20 years.
  • Smoothed percentile curves and corresponding z-scores to help plot and track the growth of children and teens (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 5 national survey datasets (Kuczmarski et al., 2000). The measurement data were collected from a series of surveys conducted by the National Center for Health Statistics from 1963 to 1994. These surveys included:

  • National Health Examination Survey (NHES), Cycle II (1963–65; ages 6–11 years)
  • NHES, Cycle III (1966–70; ages 12–17 years)
  • National Health and Nutrition Examination Survey (NHANES) I (1971–74; ages 2–19 years)
  • NHANES II (1976–80; ages 2–19 years)
  • NHANES III (1988–94; ages 2–19 years for stature, ages 2–5 years for weight and BMI)

Each of the cross-sectional surveys included a national probability sample of the civilian, noninstitutionalized US population. When the surveys were conducted, researchers applied survey-specific sample weights to the survey sample data to assure representation of the US population according to age, sex, and racial/ethnic composition.

Exclusions from the Growth Reference Population

NHANES III (1988–94) weight data for children aged 6 years and older were excluded—because of an upward shift in the weight-for-age and BMI-for-age curves, given population-level changes in body weight that occurred in the 1980s and 1990s (Kuczmarski et al., 2002). If data from NHANES III had been included, the resulting 95th percentile curve would have been higher, thus classifying fewer children and teens as having obesity.

The 2000 CDC Growth Charts: Features and Data—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 aged 2 to 20 years.

  2. When developing the 2000 CDC Growth Charts, why were the weights of children aged 6 years and older from NHANES III excluded from the growth reference data?

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