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2000 CDC Growth Charts forthe United States: Methodsand Development

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All material appearing in this report is in the public domain and may bereproduced or copied without permission; citation as to source, however, isappreciated.

Suggested Citation

Kuczmarski RJ, Ogden CL, Guo SS, et al. 2000 CDC growth charts for theUnited States: Methods and development. National Center for Health Statistics.Vital Health Stat 11(246). 2002

Library of Congress Cataloging-in-Publication Data

2000 CDC growth charts for the United States: methods and development.p. cm. (DHHS publication ; no. (PHS) 2002-1696) (Vital and health

statistics. Series 11, Data from the National Health Survey ; no. 246)May, 2002.ISBN 0-8406-0575-71. ChildrenAnthropometryUnited StatesStatistics. 2. Children

United StatesGrowthStatistics. 3. United StatesStatistics, Vital.I. Series. II. Series: Vital and health statistics. Series 11, Data from theNational Health Survey ; no. 246GN63 .A225 2001305.23'0973'021dc21 2001051405

For sale by the U.S. Government Printing OfficeSuperintendent of DocumentsMail Stop: SSOPWashington, DC 20402-9328Printed on acid-free paper.

Series 11, Number 246

2000 CDC Growth Charts forthe United States: Methodsand Development

Data From the National HealthExamination Surveys and the NationalHealth and Nutrition ExaminationSurveys

DEPARTMENT OF HEALTH AND HUMAN SERVICESCenters for Disease Control and PreventionNational Center for Health Statistics

Hyattsville, MarylandMay 2002DHHS Publication No. (PHS) 2002-1696

National Center for Health StatisticsEdward J. Sondik, Ph.D., Director

Jack R. Anderson, Deputy Director

Jack R. Anderson, Acting Associate Director forInternational Statistics

Jennifer H. Madans, Ph.D., Associate Director for Science

Lawrence H. Cox, Ph.D., Associate Director for Researchand Methodology

Jennifer H. Madans, Ph.D., Acting Associate Director forAnalysis, Epidemiology, and Health Promotion

Edward L. Hunter, Associate Director for Planning, Budget,and Legislation

Jennifer H. Madans, Ph.D., Acting Associate Director forVital and Health Statistics Systems

Douglas L. Zinn, Acting Associate Director forManagement

Charles J. Rothwell, Associate Director for InformationTechnology and Services

Division of Health Examination Statistics

Clifford L. Johnson, M.S.P.H., Director

Rosemarie Hirsch, M.D., M.P.H., Chief Analysis Branch

Carolyn Petty-Martin, Acting Chief Operations Branch

Vicki L. Burt, Sc.M., R.N., Chief Planning Branch

Lewis Berman, M.S., Chief Information Management Branch

Acknowledgments

We wish to gratefullyacknowledge the contributionsof many individuals who hadvarious roles in the growth chartrevision process. These contributionsinclude statistical and computerprogramming expertise, data andsummary statistics, graphical support,and knowledge and experience in theareas of pediatric growth and growthcharts. We also wish to thank ThelmaSanders and Zung Le for their editorialsupport. In addition to acknowledgingthe contributions of all individualsidentified in appendix I of this report,the following persons are alsorecognized, with their affiliations at thetime of their contribution:

Phil BattyCenter for Health Information

Management and EpidemiologyState of Missouri Department of HealthJefferson City, MO

Fred BuhrCenter for Health StatisticsState of Wisconsin Department of

Health and Family ServicesMadison, WI

Margaret CarrollNational Center for Health StatisticsCenters for Disease Control and

PreventionHyattsville, MD

John ChangComputer Information Systems and

Support ServicesNova Research CompanyBethesda, MD

Chris CronkCenter for Health StatisticsState of Wisconsin Department of

Health and Family ServicesMadison, WI

William DavisKlemm Analysis Group, Inc.Washington, DC

Catherine DuranNational Center for Health StatisticsCenters for Disease Control and


Odell EldridgeComputer Information Systems and

Support ServicesNova Research CompanyBethesda, MD

Stephen SloanNational Center for Health StatisticsCenters for Disease Control and


Christine ZellerDepartment of Community HealthWright State UniversityYellow Springs, OH

iii

Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Historical Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1Concerns Surrounding the 1977 Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2The Revision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Data Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Data Exclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Statistical Curve Smoothing Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Observed and Smoothed Percentiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Evaluation of the Revised Growth Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10Differences Between the 1977 NCHS and the 2000 CDC Growth Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Revision Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Growth Chart Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Major Features of the 2000 CDC Growth Charts for the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Using the Revised Growth Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Specialized Charts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13General Growth Chart Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Appendix I. Description of Growth Chart Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Workshop 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187Workshop 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188Workshop 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189Workshop 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189

Appendix Table

I. Participants in the NCHS growth chart workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

Figures

1. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

3. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Boys length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

4. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Girls length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

v

5. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Boys weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Girls weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

7. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Boys head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

8. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, birth to 36 months:Girls head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, 2 to 20 years:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

10. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, 2 to 20 years:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

11. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, 2 to 20 years:Boys stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

12. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles, 2 to 20 years:Girls stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

13. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th, 97th percentiles, 2 to 20 years:Boys body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

14. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th, 97th percentiles, 2 to 20 years:Girls body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

15. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th, 97th percentiles: Boys weight-for-stature . . . 3316. Individual growth chart 3rd, 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th, 97th percentiles: Girls weight-for-stature . . . 3417. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, birth to 36 months: Boys length-for-age

and weight-for-age percentiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3518. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, birth to 36 months: Girls length-for-age

and weight-for-age percentiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3619. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, birth to 36 months: Boys head

circumference-for-age and weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3720. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, birth to 36 months: Girls head

circumference-for-age and weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3821. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, 2 to 20 years: Boys stature-for-age and

weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3922. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 90th, 95th percentiles, 2 to 20 years: Girls stature-for-age and

weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4023. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th percentiles, 2 to 20 years: Boys body mass

index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4124. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th percentiles, 2 to 20 years: Girls body mass

index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4225. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th percentiles: Boys weight-for-stature . . . . . . . . . . . . . 4326. Clinical growth chart 5th, 10th, 25th, 50th, 75th, 85th, 90th, 95th percentiles: Girls weight-for-stature . . . . . . . . . . . . . 4427. Smoothed percentile curves, 2239 months: Boys length-for-age and stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . 4528. Smoothed percentile curves, 2239 months: Girls length-for-age and stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4629. Smoothed percentile curves, 75106 cm: Boys weight-for-length and weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . 4730. Smoothed percentile curves, 75106 cm: Girls weight-for-length and weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . 4831. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:

Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4932. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:

Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5033. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:

Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5134. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:

Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5235. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:

Boys recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5336. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:

Boys recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5437. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:

Girls recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

vi

38. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:Girls recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

39. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 46102 cm:Boys weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

40. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 46102 cm:Boys weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

41. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 46102 cm:Girls weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

42. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 46102 cm:Girls weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

43. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:Boys head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

44. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:Boys head circumference-for-age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

45. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, birth to 36 months:Girls head circumference-for-age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

46. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, birth to 36 months:Girls head circumference-for-age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

47. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 78120 cm:Boys weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

48. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 78120 cm:Boys weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

49. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 78120 cm:Girls weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

50. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 78120 cm:Girls weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

51. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

52. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 24237 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

53. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

54. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 24237 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

55. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Boys stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

56. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 24237 months:Boys stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

57. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Girls stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

58. Comparison of smoothed 5th, 25th, 50th, 75th, 95th percentile curves to empirical data points, 24237 months:Girls stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

59. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Boys body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

60. Comparison of smoothed 5th, 25th, 50th, 75th, 85th, 95th percentile curves to empirical data points,24237 months: Boys body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

61. Comparison of smoothed 3rd, 10th, 50th, 90th, 97th percentile curves to empirical data points, 24237 months:Girls body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

62. Comparison of smoothed 5th, 25th, 50th, 75th, 85th, 95th percentile curves to empirical data points, 24237 months:Girls body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

63. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

64. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

65. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

66. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

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67. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months:Boys length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

68. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Boys length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

69. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months:Girls length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

70. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Girls length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

71. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 46103 cm: Boys weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

72. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 46103 cm: Boys weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

73. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 46103 cm: Girls weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

74. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 46103 cm: Girls weight-for-length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

75. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months: Boyshead circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

76. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Boys head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

77. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, birth to 33 months:Girls head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

78. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, birth to 33 months:Girls head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

79. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 84122 cm: Boys weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

80. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 84122 cm: Boys weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

81. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 84122 cm: Girls weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

82. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 84122 cm: Girls weight-for-stature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

83. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

84. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 27237 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

85. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

86. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 27237 months:Girls weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

87. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Boys stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

88. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 27237 months:Boys stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

89. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Girls stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

90. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 95th percentile curves, 27237 months:Girls stature-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

91. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Boys body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

92. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 85th, 95th percentile curves, 27237 months:Boys body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

93. Percent of empirical data below smoothed 3rd, 10th, 50th, 90th, 97th percentile curves, 27237 months:Girls body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

94. Percent of empirical data below smoothed 5th, 25th, 50th, 75th, 85th, 95th percentile curves, 27237 months:Girls body mass index-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

95. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months: Boys weight-for-age . . . . . . . . 113

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96. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months: Girls weight-for-age . . . . . . . . . 114

97. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles withNCHS 1977 smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months:Boys recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

98. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles withNCHS 1977 smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months:Girls recumbent length-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

99. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 4994 cm: Boys weight-for-length. . . . . . . . . . . . . . 117

100. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 4994 cm: Girls weight-for-length. . . . . . . . . . . . . . 118

101. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles withNCHS 1977 smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months:Boys head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

102. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles withNCHS 1977 smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, birth to 36 months:Girls head circumference-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

103. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 91120 cm: Boys weight-for-stature . . . . . . . . . . . . 121

104. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 91120 cm: Girls weight-for-stature . . . . . . . . . . . . 122

105. Comparison of revised CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles withNCHS 1977 smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 24213 months:Boys weight-for-age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

106. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 24213 months: Girls weight-for-age . . . . . . . . . . . 124

107. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 24213 months: Boys stature-for-age . . . . . . . . . . . 125

108. Comparison of CDC 2000 smoothed 3rd, 5th, 10th, 25th, 50th, 75th, 90th, 95th, 97th percentiles with NCHS 1977smoothed 5th, 10th, 25th, 50th, 75th, 90th, 95th percentile curves, 24213 months: Girls stature-for-age . . . . . . . . . . . 126

Text Tables

A. Charts included in the 1977 NCHS Growth Charts and the 2000 CDC Growth Charts . . . . . . . . . . . . . . . . . . . . . . . . . . 2B. Source of data for each growth chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3C. Primary and supplemental data sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4D. Summary of curve smoothing procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Detailed Tables

1. Unweighted sample sizes for weight-for-age chart by sex, age, and data source: Births to 36 months . . . . . . . . . . . . . . 1272. Unweighted sample sizes for recumbent length-for-age chart by sex, age, and data source: Birth to 36 months . . . . . . 1283. Unweighted sample sizes for weight-for-recumbent length chart by sex, length interval, and data source:

Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1294. Unweighted sample sizes for head circumference-for-age chart by sex, age, and data source: Birth to 36 months . . . . 1305. Unweighted sample sizes for weight-for-stature chart by sex, stature interval, and data source: 77 to 121 cm . . . . . . . 1316. Unweighted sample sizes for weight-for-age chart by sex, age, and data source: 2 to 20 years . . . . . . . . . . . . . . . . . . . 1327. Unweighted sample sizes for stature-for-age chart by sex, age, and data source: 2 to 20 years . . . . . . . . . . . . . . . . . . . 1348. Unweighted sample sizes for body mass index (BMI)-for-age chart by sex, age, and data source: 2 to 20 years . . . . . 1369. Observed mean, standard deviation, and selected percentiles for weight (in kilograms) by sex and age:

Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13810. Observed mean, standard deviation, and selected percentiles for recumbent length (in centimeters) by sex and age:

Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13911. Observed mean, standard deviation, and selected percentiles for weight (in kilograms) by sex and recumbent length:

Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14012. Observed mean, standard deviation, and selected percentiles for head circumference (in centimeters) by sex and age:

Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

ix

13. Observed mean, standard deviation, and selected percentiles for weight (in kilograms) by sex and stature:77 to 121 cm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

14. Observed mean, standard deviation, and selected percentiles for weight (in kilograms) by sex and age:2 to 20 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

15. Observed mean, standard deviation, and selected percentiles for stature (in centimeters) by sex and age:2 to 20 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

16. Observed mean, standard deviation, and selected percentiles for body mass index (kilograms/meter2) bysex and age: 2 to 20 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

17. L, M, and S parameters and selected smoothed percentiles for weight (in kilograms) by sex and age:Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

18. L, M, and S parameters and selected smoothed percentiles for recumbent length (in centimeters) by sex and age:Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

19. L, M, and S parameters and selected smoothed percentiles for weight (in kilograms) by sex and recumbent length(in centimeters): Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

20. L, M, and S parameters and selected smoothed percentiles for head circumference (in centimeters) by sex and age:Birth to 36 months . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156

21. L, M, and S parameters and selected smoothed percentiles for weight (in kilograms) by sex and stature (in centimeters):77 to 121 cm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

22. L, M, and S parameters and selected smoothed percentiles for weight (in kilograms) by sex and age: 2 to 20 years . . 16023. L, M, and S parameters and selected smoothed percentiles for stature (in centimeters) by sex and age: 2 to 20 years . 16924. L, M, and S parameters and selected smoothed percentiles for body mass index (BMI, kilograms/meter2) by sex

and age: 2 to 20 years . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178

x

ObjectivesThis report provides detailed

information on how the 2000 Centersfor Disease Control and Prevention(CDC) growth charts for the UnitedStates were developed, expandingupon the report that accompanied theinitial release of the charts in 2000.

MethodsThe growth charts were developed

with data from five national healthexamination surveys and limitedsupplemental data. Smoothedpercentile curves were developed intwo stages. In the first stage, selectedempirical percentiles were smoothedwith a variety of parametric andnonparametric procedures. In thesecond stage, parameters were createdto obtain the final curves, additionalpercentiles and z-scores. The revisedcharts were evaluated using statisticaland graphical measures.

ResultsThe 1977 National Center for Health

Statistics (NCHS) growth charts wererevised for infants (birth to 36 months)and older children (2 to 20 years). Newbody mass index-for-age (BMI-for-age)charts were created. Use of nationaldata improved the transition from theinfant charts to those for older children.The evaluation of the charts found nolarge or systematic differences betweenthe smoothed percentiles and theempirical data.

ConclusionThe 2000 CDC growth charts were

developed with improved data andstatistical procedures. Health careproviders now have an instrument forgrowth screening that better representsthe racial-ethnic diversity andcombination of breast- and formula-feeding in the United States. It isrecommended that these charts replacethe 1977 NCHS charts when assessingthe size and growth patterns of infants,children, and adolescents.

Keywords: growth charts c height clength c weight c body mass index chead circumference c NHANES

2000 CDC Growth Charts forthe United States: Methods andDevelopmentRobert J. Kuczmarski, M.S.P.H., M.P.H., R.D., Dr.P.H., Division ofDigestive Diseases and Nutrition, National Institute of Diabetes andDigestive and Kidney Diseases, National Institutes of Health;Cynthia L. Ogden, M.R.P., Ph.D., Division of Health ExaminationStatistics; Shumei S. Guo, M.S., Ph.D.,Center for Lifetime HealthResearch, School of Medicine, Wright State University; Laurence M.Grummer-Strawn, M.A., M.P.A., Ph.D., Division of Nutrition andPhysical Activity, National Center for Chronic Disease Prevention andHealth Promotion; Katherine M. Flegal, M.S., M.P.H., Ph.D., Divisionof Health Examination Statistics; Zuguo Mei, M.P.H., M.D., Divisionof Nutrition and Physical Activity, National Center for ChronicDisease Prevention and Health Promotion; Rong Wei, M.S., Ph.D.,Office of Research and Methodology; Lester R. Curtin, Ph.D., Officeof Research and Methodology; Alex F. Roche, M.D., Ph.D., D.Sc.,F.R.A.C.P., Center for Lifetime Health Research, School of Medicine,Wright State University; Clifford L. Johnson, M.S.P.H., Division ofHealth Examination Statistics

Introduction

The National Center for HealthStatistics (NCHS) growth chartsthat have been in use since 1977have been revised. The revised version,known as the Centers for DiseaseControl and Prevention (CDC) GrowthCharts: United States released in 2000,is recommended for use in clinicalpractice and research to assess size andgrowth in U.S. infants, children, andadolescents (1).

The 2000 CDC Growth Chartsconsist of a set of charts for infants,birth to 36 months of age and a set ofcharts for children and adolescents fromages 2 to 20 years. The charts forinfants include sex-specific smoothedpercentile curves for weight-for-age,recumbent length-for-age, headcircumference-for-age, and weight-for-recumbent length; the charts for childrenand adolescents include weight-for-age,

stature-for-age, and body mass index(BMI)-for-age curves. The BMI-for-agecharts represent a new tool that can beused by health care providers for theearly identification of children who areat risk for becoming overweight at olderages. The 2000 CDC Growth Chartsalso include weight-for-stature charts forstatures ranging from 77 to 121 cm,primarily intended for use amongchildren from ages 2 to 5 years. Alisting of the 1977 NCHS charts and the2000 CDC charts is shown in table A.

Historical BackgroundAnthropometric data are valuable

objective indicators of attained size andphysical growth in children. A variety ofgrowth references were developed andused in the United States since the early1900s. Most of these earlier referenceshave considerable limitations, includinglack of coverage for infants andpreschool children and limited

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[ Series 11, No. 246

representation of ethnic, genetic,socioeconomic, environmental, andgeographic variability (2). From19461976, the Stuart/Meredith GrowthCharts were widely used. These chartswere derived from stature and weightmeasurements taken on white childrenliving near Iowa City, Iowa, or inBoston, Massachusetts, from 1930 to1945 (3). The sample sizes wererelatively small and the smoothedpercentile lines were reportedly basedon mathematical approximations ofcurves smoothed by hand (4). Thus, thedata did not represent the diversity ofchildren residing in the United Statesand statistical curve-fitting procedureswere not used.

The impetus for the development ofthe 1977 NCHS Growth Charts began in1971, when a study group sponsored bythe American Academy of Pediatrics andthe Maternal and Child Health Programof the Bureau of Community HealthServices, U.S. Public Health Service,recommended new growth charts, basedon data from the NCHS HealthExamination Surveys, for the clinicalassessment of infants and children (5).Subsequently, in 1974, the Food andNutrition Board of the NationalAcademy of Sciences made similarrecommendations, emphasizing the needfor new growth charts for infants andchildren based on nationallyrepresentative survey data, to besupplemented with data collected frominfants in the Fels Longitudinal GrowthStudy (6). These recommendations werefurther supported in 1975 by a studygroup sponsored by the NationalInstitute of Child Health and HumanDevelopment, National Institutes ofHealth (7).

Growth charts for the United Stateswere developed by NCHS whennationally representative cross-sectionalsurvey data became available for mostof the pediatric age range (8). Data fromthe National Health Examination Survey(NHES) II (196365) for ages 611years, NHES III (196670) for ages1217 years, and the first NationalHealth and Nutrition ExaminationSurvey (NHANES) I (197174) for ages117 years were used to develop thesecharts. National survey data were notavailable for the period from birth to 1

year. Therefore, the national survey datawere supplemented with data from thelongitudinal growth study of the FelsResearch Institute in Yellow Springs,Ohio. To avoid pooling multiple diversedata sets in the 1977 NCHS charts forbirth to 3 years, the infant charts werebased solely on the Fels data. The 14sex-specific growth charts developed forinfants birth to age 36 months and olderchildren from ages 2 to 18 years aregenerally referred to as the 1977 NCHSGrowth Charts (2,8,9).

In 1978 CDC produced anormalized version of the NCHScurves (10,11). The World HealthOrganization (WHO) subsequentlyrecommended these normalized chartsfor international applications (1214).These normalized versions of the 1977charts are thus sometimes referred to asthe NCHS/WHO, CDC/WHO, orNCHS/CDC/WHO growth charts.Following the recommendation ofWaterlow, et al., this version enabled theexpression of body measurements interms of standard deviations from themedian or z-scores (15). Z-scoresfacilitate comparisons across ages andallow the mean and standard deviationto be calculated for a group ofmeasures. Another advantage of the

normalized charts was the ability todescribe the relative status of children atextremes of the distributions.

Although the normalized chartsallowed users a means to better quantifygrowth at the extremes, normalizationdoes not refer to an improvedinstrument to qualify growth asnormal or as a standard for growth.Both the 1977 smoothed percentiles andthe 1978 normalized growth curves aregrowth references. They allow thegrowth status of a child, or a group ofchildren, to be compared with that of areference population. The 1978normalized curves are similar to, but notidentical with the 1977 smoothedpercentiles.

Concerns Surrounding the1977 Charts

Since the development of the 1977NCHS Growth Charts, a number ofconcerns have been raised about variousaspects of the charts and the proceduresused in their development (10,1623).Most of these concerns centered on theinfant charts and were largely associatedwith characteristics of the Fels data. TheFels data came from a singlelongitudinal study of mainly formula-

Table A. Charts included in the 1977 NCHS Growth Charts and in the 2000 CDC GrowthCharts

1977 NCHS Growth Charts* 2000 CDC Growth Charts*

Weight-for-ageBirth to 36 months2 to 18 years

Length-for-ageBirth to 36 months

Weight-for-lengthBirth to 36 months

Boys (49 to 103 cm)Girls (49 to 101 cm)

Head circumference-for-ageBirth to 36 months

Stature-for-age2 to 18 years

Weight-for-stature**Boys (90 to 145 cm)Girls (90 to 137 cm)

Weight-for-ageBirth to 36 months2 to 20 years

Length-for-ageBirth to 36 months

Weight-for-lengthBirth to 36 months

Boys (45 to 103 cm)Girls (45 to 103 cm)

Head circumference-for-ageBirth to 36 months

Stature-for-age2 to 20 years

Weight-for-stature**Boys (77 to 121 cm)Girls (77 to 121 cm)

BMI-for-age2 to 20 years

*All charts are sex-specific.**The 1977 charts are applicable to boys with stature from 90 to 145 cm and age under 11.5 years, and to girls with stature from90 to 137 cm and under 10.0 years of age. They are not applicable for any child showing the earliest signs of pubescence. Therevised charts have no similar age or pubescence restrictions. Although the revised charts were developed for children 2 to 5 yearsof age, in practice they may accommodate some shorter children with chronologic ages 5.0 years and over.

Series 11, No. 246 [ Page 3

fed, white middle-class infants in alimited geographic area of southwesternOhio, collected 192975. In addition tonot being from a nationallyrepresentative sample, the Felsobservations were made at birth and 1month, at 3-month intervals from 3 to12 months, and at 6-month intervalsfrom 12 to 36 months. These intervalsmay be inadequate to properly identifygrowth patterns during periods of rapidchange. The Fels birthweights may notmatch more recent national birthweightdistributions, and differences betweenrecumbent length and stature may havebeen too large, suggesting limitations inthe recumbent length data. Moreover,size and growth patterns of Fels infantsmay not adequately represent currentgrowth patterns of combined breast- andformula-fed infants in the population(8,18,19,21,22). In addition, differencesbetween the recumbent lengthmeasurements for infants from the Felsdata and the stature measurements fromthe NCHS data sets lead to inconsistentpercentile estimates from the 1977charts when the transition is made fromrecumbent length to stature between 24and 36 months of age. Other concernsincluded the limited ability to assesssize and growth at extremes beyond the5th and 95th percentiles, the absence of

weight-for-stature references foradolescents, and the inability to assessgrowth at ages 18 years and over (16).

The RevisionThe 1977 charts were revised in

part because more recent andcomprehensive national data on bodymeasurements in U.S. children wereavailable. After the 1977 NCHS GrowthCharts were developed, additionalnational survey data became availablefrom the NHANES II (197680)beginning at 6 months of age, and fromthe NHANES III (198894) beginningat 2 months of age (24,25). During theplanning of NHANES III, increasingawareness of the concerns surroundingthe 1977 NCHS Growth Chartsinfluenced the decision to oversamplechildren ages 2 months to 6 years.

The objective of the revisionprocess was to use improved statisticalsmoothing procedures, in conjunctionwith more comprehensive nationalsurvey data, to provide a betterinstrument for health care providers whoevaluate the growth status of children inthe United States (16). The AdvanceData report summarizing thedevelopment of the revised growthcharts was issued in 2000 (1). The

present report is designed to expand onthe content of the initial report andprovide more detailed information onthe development of the revised CDCgrowth charts for the United States,including the process, the data sources,the statistical procedures that werefollowed, and the results of statisticalevaluations for the revised charts.

Methods

Data SourcesThe source of data for each growth

chart is shown in table B. The primaryand supplemental data sources aresummarized in table C. Detailed samplesizes for the data used to create eachchart, stratified by age, sex, and datasource, are shown in detailed tables 18.

National Data

The revised growth curves for theUnited States were developed with datacollected by NCHS in five cross-sectional, nationally representativehealth examination surveys (table C):the NHES II (196365) and III(196670), and NHANES I (197174),

Table B. Source of data for each growth chart

ChartAge (months) or

height (cm) range Primary data sources1 Supplemental data sources

Weight-for-age Birth to 36 months National surveys 352 National birth certificate data fromUnited States Vital Statistics2

Length-for-age Birth to 36 months National surveys 352,3 Birth certificate data from Wisconsinand Missouri State vital statistics2,4;CDC Pediatric Nutrition SurveillanceSystem data for 0.5, 1.5, 2.5, 3.5, and4.5 months2

Head circumference-for-age Birth to 36 months National surveys 352 Fels Longitudinal Study data2

Weight-for-length 45 to 103 cm National surveys 352,5 Birth certificate data from Wisconsinand Missouri State vital statistics2

Weight-for-stature 77 to 121 cm National surveys 355 None

Weight-for-age 24 to 240 months National surveys 155 None

Stature-for-age 24 to 240 months National surveys 15 None

BMI-for-age 24 to 240 months National surveys 155 None

1Survey 1 = NHES II, Survey 2 = NHES III, Survey 3 = NHANES I, Survey 4 = NHANES II, and Survey 5 = NHANES III.2Excludes birthweight


II (197680), and III (198894). Thesurvey designs are based on stratified,multistage probability samples of thecivilian, noninstitutionalized populationin the 48 contiguous States (NHES II,NHES III, NHANES I) or all 50 States(NHANES II, NHANES III). Allsurveys consisted of a home interviewand a standardized physical examinationconducted in a mobile examinationcenter. Age was calculated as age at thetime of examination when theanthropometric data were recorded.Children ages 611 years from NHESII, 1217 years from NHES III, 119years from NHANES I, six months19years from NHANES II, and 2months19 years from NHANES IIIwere included in the revision. The small

number of children in NHES II who hadtheir 12th birthday after the homeinterview and before the examinationand those who had their 18th birthdayafter the home interview and before theexamination in NHES III were alsoincluded. Although the revised growthcharts for older children were developedfor ages from 2 to 20 years, additionalNHANES data for individuals youngerthan 2 years and older than 20 yearswere included in the analysis to improveestimates at the lower and upperboundaries (table C). Detaileddescriptions of these surveys have beenprovided (2529).

Anthropometric proceduresdeveloped for NHANES III aredocumented on videotape

URL: http://www.cdc.gov and in theNHANES III procedures manual (30).The procedures were consistent withpublished recommendations forstandardized anthropometrictechniques (31). The NHANES IIImeasurement techniques for weight,recumbent length, stature, and headcircumference were based onprocedures used in the previous NHESand NHANES surveys, and either thesame or comparable measuringequipment was used across thesurveys.

Supplemental Data

For the infant charts, a limitednumber of additional data points

Table C. Primary and supplemental data sources

Data set Years Data source Subject1 Sex Chart2

Primary data sets

NHES II 196365 National survey Age (months): 72.0145.9 M, F W, S, BMI

NHES III 196670 National survey Age (months): 144.0217.9 M, F W, S, BMI

NHANES I 197174 National survey Age (months): 12.023.912.035.912.0281.9

M, FM, FM

LHCW

12.0245.9 F W18.0305.9

Length (cm): 65109Stature (cm): 77127

M, F S, BMIWLWS

NHANES II 197680 National survey Age (months): 6.035.96.0281.9

M, FM

L, HCW

6.0245.9 F W18.0305.9


M, F S, BMIWLWS

NHANES III 198894 National survey Age (months): 3.035.92.035.92.071.918.0305.93

18.071.93


M, FM, FM, FM, FM, F

LHCWSBMIWLWS

Supplemental data sets

United States Vital Statistics 196880;198594

Birth certificates Age: birth M, F W

State of Wisconsin Vital Statistics 198994 Birth certificates Age: birthBirth length (cm): 4552.9

M, F LWL

State of Missouri Vital Statistics 198994 Birth certificates Age: birthBirth length (cm): 4552.9

M, F LWL

Fels Longitudinal Study 196094 Hospital records4 Age: birth M, F HC

Pediatric Nutrition SurveillanceSystem5

197595 Clinic records Age (months): 0.14.9 M, F L

1Data from outside the 2 to 20-year range for the child/adolescent charts were used to improve estimates at the upper and lower age boundaries. Subject ages, shown for growth chart variables,reflect the endpoints of age ranges for data actually used to construct the smoothed percentile curves.2W = weight-for-age; S = stature-for-age; BMI = body mass index-for-age; L = length-for-age; HC = head circumference-for-age; WL = weight-for-length; WS = weight-for-stature.3Lengths at ages 18.023.99 months, and stature at all other ages.4Majority measured in hospital by Fels staff.5Selected clinics.

http:http://www.cdc.gov


obtained from other sources wereincorporated at birth and during the firstfew months of life where national datawere either not available or wereinsufficient (table C). The infantweight-for-age curves included nationalbirthweight distributions taken frombirth certificates for more than 83million infants born in the United Statesbetween 196880 and 198594,corresponding to years in which infantsin the national surveys were born. Birthlength data were only available fromtwo States, Wisconsin and Missouri.These States recorded this informationon birth certificates for 890,000 infantsborn between 1989 and 1994. Thesedata were used in the development ofthe length-for-age and weight-for-lengthcurves. Additionally, a limited amountof data from the CDC PediatricNutrition Surveillance System (PedNSS)was used in the length-for-age charts.The majority of infant data in thePedNSS system come from clinicalrecords of the Special SupplementalNutrition Program for Women, Infantsand Children (WIC) (20). Because thePedNSS data are not nationallyrepresentative, a subset of the PedNSSdata collected from 1975 to 1995 wasused. Clinics were selected for inclusionbased on three specific conditions. First,the mean lengths and weights had to bewithin 0.5 cm and 0.5 kg of the meanfrom NHANES II and III combined foreach single month of age from age 3 to11 months. Second, the clinics had tohave a SD within 0.2 cm and 0.2 kgof the SDs in the combined NHANES IIand III. Finally, the skewness in weightdistribution of the selected clinicspopulation had to be within 0.3 kg ofthe skewness of weight in the combinedNHANES II and III. A total of 213PedNSS clinics were selected, resultingin a sample of 14,846 observations at0.5 months, 8,825 at 1.5 months, 5,240at 2.5 months, 1,640 at 3.5 months, and2,258 at 4.5 months. All the matchingprocedures excluded subjects withbirthweights


Table D. Summary of curve smoothing procedures

Curve Curve smoothing procedures

Weight-for-age For birth to 36 months, a 3-parameter linear model fit to empirical percentile points for weight at midpoints of age intervals, andanchored (i.e., forced) at birth and at 2.75 years. Averages of weighted empirical percentiles at 2.25 and 2.75 years (based on dataused for birth to 36 months and 2 to 20 years) substituted for data points in the 24 to 36 months range.

For 2 to 20 years, locally weighted regression (LWR) based on 15-point smoothing for boys and 17-point smoothing for girls. Fit toempirical percentile points for weight at midpoints of age intervals, combined averages of weighted empirical percentiles at 2.25 and2.75 years (based on data used for birth to 36 months and 2 to 20 years), and predicted values for 2 to 3 years at 0.1 year intervalsfrom the 3-parameter linear model used for birth to 36 months.

All results from the 3-parameter linear model and LWR were combined and refit at midpoints of age intervals from birth to 20 yearsusing a 10-parameter polynomial regression model for boys and 9-parameter polynomial regression model for girls.

Length-for-age andStature-for-age

For length-for-age, birth to 36 months, a 3-parameter linear model was fit to empirical percentile points for length at midpoints of ageintervals and to birth data.

For stature-for-age, 2 to 20 years, a 10-parameter nonlinear model was fit to empirical points for stature at midpoints of age intervals.

Results from the 3-parameter linear model used for length-for-age were adjusted by subtracting 0.8 cm from length to make lengthcontinuous with stature in the overlapping age interval of 24 to 36 months. Percentiles in the overlap period were averaged byassigning weights of 1, 11/12, ..., 1/12, 0 at 24, 25, ..., 35, 36 months, respectively, to the adjusted length-for-age. Opposite weightsof 0, 1/12, ..., 11/12, 12/12 at 24, 25, ..., 35, 36 months, respectively, were assigned to smoothed stature-for-age percentiles. Thefinal length-for-age and stature-for-age curves were created by adding back 0.8 cm to the smoothed length.

Head circumference-for-age

For birth to 36 months, a 3-parameter linear model was fit to empirical percentile points for head circumference at midpoints of ageintervals and to birth data.

Weight-for-length andWeight-for-stature

Empirical weight-for-length data were adjusted by subtracting 0.8 cm from length to make length continuous with stature in theoverlapping age interval of 24 to 36 months. The combined adjusted weight-for-length and weight-for-stature data were smoothedwith a 5-parameter polynomial regression model, fit to empirical percentile points for weight at midpoints of 2 cm intervals. Afterapplying LMS, separate weight-for-length curves were created by adding 0.8 cm back to length.

BMI-for-age For 2 to 20 years, LWR model was based on a 5-point smoothing at midpoints of age intervals for ages 2 to 12.5 years, and a25-point smoothing for boys and a 27-point smoothing for girls for ages 13 to 20 years. The curves were further smoothed with a4-parameter polynomial regression model fit to smoothed percentile points for BMI at midpoints of age intervals.

in detail for each chart and aresummarized in table D.

Age and Length Groupings

Before smoothing, data were groupedby single month of age for thedevelopment of charts relating size to age.Each month of age was truncated to thenearest completed month, for example, 1month (1.01.9 months), 11 months(11.011.9 months), 23 months (23.023.9months), and so forth. From birth to 12months, the empirical percentileestimates were made at 1-monthintervals; from 12 to 24 months, theempirical percentile estimates weremade at 3-month intervals; and at 24months and beyond, empirical percentileestimates were made at 6-monthintervals. All ages were labeled as themidpoint of the defined age groups. Forthe infant charts, infants were groupedas follows: 0.5 months = 0.10.9months (birth was not included),1.5 months = 1.01.9 months, ...,11.5 months = 11.011.9 months;13.5 months = 12.014.9 months,16.5 months = 15.017.9 months,19.5 months = 18.020.9 months,22.5 months = 21.023.9 months;

27.0 months = 24.029.9 months, and33.0 months = 30.035.9 months.For the charts for older children andadolescents, subjects were separated into36 half-year age groups. Each age groupwas categorized by the midpoint of anage range. For example, age 2.25 yearsincluded ages from 2.0 years to 2.5years of age. This pattern continued upto the 19.75 year age interval in whichthe age range is from 19.5 to 20.0 yearsof age.

Before smoothing, the length andstature data were grouped by 2-cmintervals. For example, 46 cm =4546.9 cm.

Curve Smoothing Stage

For each growth chart, the initialsmoothing methods were applied to nineempirical percentiles (3rd, 5th, 10th,25th, 50th, 75th, 90th, 95th, and 97th).In addition, the 85th percentile wasincluded in the BMI-for-age chartsbecause the 85th percentile of BMI hasbeen recommended as a cutoff toidentify children and adolescents at riskfor overweight (34,35).

The weighted empirical percentileestimates were obtained by applying the

survey-specific sample weights tocalculate weighted empirical percentilepoints at the midpoint of each age group(or the midpoint of each 2-cm intervalfor length or stature). The irregular plotsof empirical percentile values had to besmoothed to produce clinically usefulpercentile curves.

Several different approaches wereused in the smoothing stage. Theempirical percentiles for infant weight,length, and head circumference weresmoothed using a family of three-parameter linear models that have beenused previously to describe age-relatedchanges in growth from birth to age 36months (3638). Stature-for-age wassmoothed using a nonlinear modelwhereas weight-for-stature andweight-for-length were smoothed usinga 5-degree polynomial regression model.Two-step smoothing was applied toweight-for-age in infants and olderchildren and BMI-for-age. In the firststep of smoothing weight-for-age andBMI-for-age for older children, locallyweighted regression (LWR) was used.Polynomial regression was used in thesecond step of smoothing weight-for-ageand BMI-for-age. The smoothing stageresulted in every chart having a


parametric form with estimatedparameters specific for each selectedmajor percentile.

The parameters of the linearregressions were estimated using theSAS procedure REG, and the parametersin the nonlinear regression wereestimated using the SAS procedureNLIN (39). The fit of the models wasevaluated using root mean square error(RMSE), R2, and CV (40).

The Transformation Stage

In order to estimate any percentileand allow calculation of standarddeviation units and z-scores, a modifiedLMS statistical procedure was applied tothe smoothed percentile curves. TheLMS method does not change thedistribution of percentile curves in agrowth chart; rather it provides a way toestimate percentiles in a continuousmanner.

The distribution of someanthropometric data used in the growthcharts are skewed. To remove skewness,a power transformation can be used tostretch one tail of the distribution whilethe other tail is shrunk. A Box-Coxtransformation can make the distributionnearly normal (41). The assumption isthat, after the appropriate powertransformation, the data are closelyapproximated by a normaldistribution (42). The transformationdoes not adjust for kurtosis, which is aless important contributor tononnormality than skewness (43).

In the LMS technique, threeparameters are estimated: the median(M), the generalized coefficient ofvariation (S), and the power in theBox-Cox transformation (L). The Lreflects the degree of skewness. TheLMS transformation equation is:

X = M (1 + LSZ)1/LL 0 or

X = M exp(SZ) L = 0

where X is the physical measurementand Z is the z-score that corresponds tothe percentile.

The key task of the transformationwas to estimate parameters L, M, and S.With estimates of L, M, and S, values ofX are connected to the values of Zthrough the above equation. The

percentile is obtained from a normaldistribution table where the z-scorecorresponds to the percentile of interest.For example, a z-score of 0.2019corresponds to the 58th percentile. Inthe case of growth charts, with the L, M,and S parameters, it is possible toevaluate any single measure in apopulation as an exact z-score orpercentile.

To generate age-specific estimatesof L, M, and S, Cole (42,44) hasrecommended applying a penalizedlikelihood estimation procedure to theraw data. In this approach smoothedcurves of L, M, and S are generatedfirst, and then smoothed percentilecurves, or an individual standardizedscore, can be obtained from the valuesof L, M, and S.

In contrast to the original LMSprocedure, a modified LMS estimationprocedure was created and used togenerate the 2000 CDC Growth Charts.In the modified LMS approach,empirical percentile curves were initiallysmoothed and parametric models weregenerated, as described above. Then, ateach age or length/stature interval, agroup of 9 equations (10 for BMIcharts) was generated by specifying theLMS transformation equations for thepreviously smoothed major percentiles.A simultaneous solution for the threeparameters of L, M, and S from thegroup of specified equations wasgenerated using the SAS procedureNLIN (39). By minimizing the sum ofsquared errors, the set of L, M, and Sparameters was obtained as the bestsolution to a system of equations ratherthan as likelihood-based estimates fromempirical data. This approach is similarto the method used by Cole to estimateLMS parameters from publishedpercentile curves (4547).

This modified LMS procedureproduced final curves that are extremelyclose to the smoothed percentile curvesobtained from the first stage ofsmoothing. The net result is that theclose fit of the smoothed curves fromthe first stage of smoothing to theempirical data is retained. In addition,the modified LMS method allowsz-scores to be obtained in a continuousmanner. The LMS values werecalculated by solving equations that

used the values for percentiles rangingfrom the 3rd to the 97th. Percentiles lessthan the 3rd or greater than the 97th arebeyond the range of the data fromwhich the LMS parameters werecalculated. As in any statisticalprocedure, extrapolation beyond therange of the data should be done withcaution.

The final set of percentile curvesfor the CDC growth charts presented inthis report was produced using thismodified LMS estimation procedure. Inthe transformation stage, percentileswere developed at 1-month or1-centimeter intervals in the infant andchild charts. Estimates of L, M, and Sparameters in these intervals werecalculated to provide the necessary toolsfor determining additional percentiles.Generally, 1-month or 1-centimeterintervals will be adequate for estimationor evaluation. To obtain percentiles atfiner intervals, the L, M, and S valuescould be interpolated.

Detailed Procedures by Chart

Weight-for-Age

Combining infant and child/adolescentweight-for-ageAfter the infantweight-for-age and child/adolescentweight-for-age curves were smoothedusing a 3-parameter linear model andLWR, the results were combined andrefit from birth to age 20 years using asingle regression model for each sex.The smoothed weight-for-age curves forinfants and for older children werecombined to obtain a seamless transitionbetween the curves. Ultimately thecombined weight-for-age curve wasseparated into infant and child/adolescent curves to facilitate use inclinical settings.

In order to combine the infant andchild/adolescent weight-for-age curves,weighted averages of overlappingempirical percentiles from infant andchild charts at 2.25 years (24.029.9months) and 2.75 years (30.035.9months) were calculated using thecombined infant and child/adolescentdata. The empirical percentiles were notidentical at ages 2436.9 monthsbecause VLBW infants (

percentiles, but included in the olderchild percentiles where the effect ofVLBW is diminished. The averagedpercentiles were substituted for theempirical values in smoothing theweight-for-age for infants andweight-for-age for children/adolescents.These combined percentile curves werefit by a 10-degree polynomial for boysand by a 9-degree polynomial for girls.A set of nine polynomial regressionequations, one for each of the majorsmoothed percentiles, was solvedsimultaneously for infants and forchildren to estimate the L, M, and Sparameters for boys and for girlsseparately.

Weight-for-age, birth to 36 monthsThe infant weight-for-age curves forages birth to 36 months were smoothedinitially with a 3-parameter linearmodel:

f(t) = a+b * ln(t+0.5) + c(t+0.5)0.75

where f(t) is body weight in kg, t is agein months (calculated as midpoint of theage range), and a, b, and c areparameters to be estimated. Theestimated values of f(t) are the smoothedvalues. At birth, t = 0. Estimates of a, b,and c are specific for each of ninepercentiles being smoothed. Anexponent of 0.75 was selected based onthe evaluation of RMSE after severalmodels were tried, beginning with theexponent of 0.3.

After excluding birthweights


1/12, 0 to values of length-for-age at 24,25, 26, ..., 35, 36 months, respectively,and assigning opposite weights of 0, 1/12,..., 11/12, 1 to values of stature-for-age at24, 25, ..., 35, 36 months, respectively.These weighted average percentile valuesin the overlapping section were shared byboth charts. Length-for-age was readjustedby adding back 0.8 cm to length,producing separate length-for-age andstature-for-age curves. This resulted in thetwo sets of parallel percentiles with aconsistent separation of 0.8 cm in theoverlapping section.

Two sets of nine equations (one setfor length-for-age and one set forstature-for-age), for each of the majorsmoothed percentiles, were solvedsimultaneously to estimate the L, M, andS parameters for boys and girlsseparately. The nine final percentilecurves for infants and children werepredicted using the estimated L, M, andS values.

Length-for-age, birth to 36 monthsTheinfant recumbent length-for-age curves forages birth to 36 months were smoothedwith a 3-parameter linear model:

f(t) = a+b * ln (t+1) + c(t+1)0.5

where f(t) is length in cm, t is age inmonths (calculated as midpoint of theage range), and a, b, and c areparameters to be estimated. Theestimated values of f(t) are the smoothedvalues. At birth, t = 0. Estimates of a, b,and c are specific for each of ninepercentiles being smoothed.

After excluding birthweights


to 109 cm and available weight-for-stature data ranged from 77 to 127 cmfor calculating empirical percentiles.After the final curve smoothing,weight-for-length was truncated to103 cm and weight-for-stature wastruncated to 121 cm on the final charts.

A set of nine 5-degree polynomialregression equations, one for each of themajor smoothed percentiles for thecombined weight-for-length andweight-for-stature data, was solvedsimultaneously to estimate the L, M, andS parameters for boys and girlsseparately. The nine final percentilecurves for infants were predicted usingthe estimated L, M, and S values. Toobtain separate weight-for-length andweight-for-stature curves, 0.8 cm wasadded back to all the smoothed lengthvalues. This was accomplished byshifting back the corresponding lengthvalues for the length-specific weight, L,M, and S, by 0.8 cm to form theweight-for-length measure from theweight-for-stature scale. The 85thpercentile of weight-for-stature wascalculated subsequently from the L, M,and S values.

Body Mass Index-for-Age

Empirical percentiles from thenational data were smoothed with LWR.Ten empirical percentiles werecalculated for the BMI-for-age chartsbecause the additional 85th percentilewas required for boys and girls toidentify children and adolescents at riskfor overweight. Each smoothed valuewas estimated by weighted linearregression on the five-neighborhoodpoints adjacent to the value to beestimated from ages 2 to 12.5 years.From 13 to 20 years, a 25-pointsmoothing procedure was used for boysand a 27-point smoothing procedure wasused for girls. At the lower end (that is,age 2 years), two additional points wereneeded in the smoothing window, so aneighborhood point of 1.75 years wasused for BMI. This was calculated usingunadjusted recumbent length, repeated at1.75 and at 1.71 years for both sexes. Atthe upper end (that is, age 20 years), themaximum BMI values in each empiricalpercentile from age 19.75 through 25.25years were chosen and repeated in0.5-year intervals from 20.25 through

25.75 years for boys or from 20.25through 26.25 years for girls. Takingmaximum values as additional data insmoothing the windows ensured that theBMI curves did not increase beyond themaxima at the upper ends of the ageranges. The smoothed percentile curvesobtained through LWR were then fit bya 4-degree polynomial regression toachieve parametric percentiles. (Seesection on weight-for-age, 2 to 20 years,above, for further description of LWR.)

A set of 10, 4-degree polynomialregression equations, 1 for each of themajor smoothed percentiles, was solvedsimultaneously to estimate the L, M, andS parameters for boys and girlsseparately. The 10 final percentilecurves for infants were predicted usingthe estimated L, M, and S values.

Results

Observed and SmoothedPercentiles

The observed percentile distributions,along with means and standard deviations,are shown by sex and age in detailedtables 916. Selected smoothed percentiles(3rd, 5th, 10th, 25th, 50th, 75th, 90th,95th, and 97th for all charts, and 85th forBMI-for-age and weight-for-stature) areshown in detailed tables 1724 for the 16age- and sex-specific growth charts. Alsopresented in these tables are the L, M, andS parameters that were used to create thefinal charts and are needed to generateadditional percentiles and z-scores.

The smoothed 3rd, 5th, 10th, 25th,50th, 75th, 90th, 95th, and 97thpercentile curves that constitute the 16individual CDC growth charts for theUnited States are shown in figures 116.In addition, the 85th percentile is shownin figures 13 and 14 for BMI-for-ageand in figures 15 and 16 for weight-for-stature. Two additional sets of individualcharts not shown in this report areavailable on the Internet (www.cdc.gov/growthcharts). One set shows curvesranging from the 5th to 95th percentiles(without the 3rd and 97th), and anotherset has the 3rd to 97th percentiles(without the 5th and 95th).

The growth charts shown infigures 114 have a primary scale inEnglish units (lb, in), and a secondaryscale in metric units (kg, cm), except inthe BMI-for-age charts where there aresingle scales (kg/m2) as shown infigures 15 and 16.

Figures 1726 show the chartsdeveloped for clinical use depicting the5th, 10th, 25th, 50th, 75th, 90th, and95th percentiles, and 85th forBMI-for-age and weight-for-stature. Thisformat has two charts per page andincludes tables for recordingmeasurement data. For the clinicalcharts, the primary scale is metric andthe secondary scale is English. Acomparable set of clinical charts withthe 3rd and 97th percentiles in place ofthe 5th and 95th not shown in thisreport is available on the Internet(www.cdc.gov/growthcharts).

Evaluation of the RevisedGrowth Curves

After the initial smoothing andtransformation stages were completed,the percentile curves were evaluated.Transitions between the infant and olderchild charts were reviewed and eachmajor percentile curve (3rd, 5th, 10th,25th, 50th, 75th, 90th, 95th, 97th, and85th for BMI-for-age) was comparedgraphically with the correspondingempirical data. In addition, the percentof empirical data below the smoothedpercentiles was calculated and comparedwith the expected values. The objectiveof these procedures was to search forany large or systematic differencesbetween the smoothed percentiles andthe empirical data.

Evaluation of the transitionsbetween the charts from birth to 36months to the charts from 2 to 20 yearsindicated that disjunctions that werepresent in the 1977 NCHS charts werenot present in the 2000 CDC charts. Thefinal charts for length-for-age andstature-for-age were constructedsimultaneously with an imposed parallelseparation of 0.8 cm, based on theaverage difference between measuredlength and stature. Consequently, thesmoothed percentile curves forlength-for-age and stature-for-age are

www.cdc.gov/growthchartshttp:www.cdc.gov


parallel to each other as shown infigures 2728. A child should havesimilar values for length-for-age orstature-for-age. Weight-for-length andweight-for-stature were constructed withan imposed offset of 0.8 cm (figures 29and 30).

The results of graphicalcomparisons for evaluation of the finalcurves are shown in figures 3162.Overall, the smoothed curves fit theempirical data well, without anysystematic departures. This wasparticularly true for stature-for-age(figures 5558). Nevertheless, for all thecurves, the empirical data points at theouter percentiles tended to be moreirregular relative to those at the morecentral percentiles.

Although the performance of thefinal smoothed curves was judgedacceptable, the weight-for-age curvesdiverged from the empirical data pointsat some ages, even at the median, whereestimates generally are expected to bemost stable.

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