WWHHOO CChhiilldd GGrroowwtthh SSttaannddaarrddss In 1993 the World Health Organization (WHO) undertook a Head circumference-for-age, arm circumference-for-age, comprehensive review of the uses and interpretation of triceps skinfold-for-age and subscapular skinfold-for-age anthropometric references. The review concluded that the NCHS/WHO growth reference, which had been recommended for Methods and development international use since the late 1970s, did not adequately represent early childhood growth and that new growth curves were necessary. The World Health Assembly endorsed this recommendation in 1994. The WHO Multicentre Growth Reference Study (MGRS) was undertaken in response to that endorsement and implemented between 1997 and 2003 to generate new curves for assessing the growth and development of children the world over. The MGRS collected primary growth data and related information from 8440 healthy breastfed infants and young children from diverse ethnic backgrounds and cultural settings (Brazil, Ghana, India, Norway, Oman and USA). The growth standards developed based on these data and presented in this report provide a technically robust tool that represents the best description of physiological growth for children under five years of age. The standards depict normal early childhood growth under optimal environmental conditions and can be used to assess children everywhere, regardless of ethnicity, socioeconomic status and type of feeding. 1 year 2 years 3 years 4 years 5 years ISBN 9789241547185 WWHHOO CChhiilldd GGrroowwtthh SSttaannddaarrddss Head circumference-for-age, arm circumference-for-age, triceps skinfold-for-age and subscapular skinfold-for-age Methods and development Department of Nutrition for Health and Development WHO Library Cataloguing-in-Publication Data WHO child growth standards : head circumference-for-age, arm circumference-for- age, triceps skinfold-for-age and subscapular skinfold-for-age : methods and development. Coordinating team: Mercedes de Onis ... [et al.]. 1.Anthropometry. 2.Anthropometry - methods. 3.Body size - standards. 4.Child development. 5.Growth. 6.Reference standards. 7.Nutrition assessment. I.de Onis, Mercedes. II.World Health Organization. III.Title: World Health Organization child growth standards. ISBN 978 92 4 154718 5 (NLM classification: WS 103) © World Health Organization 2007 All rights reserved. Publications of the World Health Organization can be obtained from WHO Press, World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; fax: +41 22 791 4857; e-mail: [email protected]). Requests for permission to reproduce or translate WHO publications – whether for sale or for noncommercial distribution – should be addressed to WHO Press, at the above address (fax: +41 22 791 4806; e-mail: [email protected]). The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. The mention of specific companies or of certain manufacturers’ products does not imply that they are endorsed or recommended by the World Health Organization in preference to others of a similar nature that are not mentioned. Errors and omissions excepted, the names of proprietary products are distinguished by initial capital letters. All reasonable precautions have been taken by the World Health Organization to verify the information contained in this publication. However, the published material is being distributed without warranty of any kind, either expressed or implied. The responsibility for the interpretation and use of the material lies with the reader. In no event shall the World Health Organization be liable for damages arising from its use. Printed in China, Hong Kong Special Administrative Region. Members of the WHO Multicentre Growth Reference Study Group Coordinating Team Mercedes de Onis [Study Coordinator], Adelheid Onyango, Elaine Borghi, Amani Siyam, Alain Pinol (Department of Nutrition for Health and Development, World Health Organization). Executive Committee Cutberto Garza [Chair], Mercedes de Onis, Jose Martines, Reynaldo Martorell, Cesar G. Victora (up to October 2002), Maharaj K. Bhan (from November 2002). Steering Committee Coordinating Centre (WHO, Geneva): Mercedes de Onis, Jose Martines, Adelheid Onyango, Alain Pinol. Investigators (by country): Cesar G. Victora and Cora Luiza Araújo (Brazil), Anna Lartey and William B. Owusu (Ghana), Maharaj K. Bhan and Nita Bhandari (India), Kaare R. Norum and Gunn- Elin Aa. Bjoerneboe (Norway), Ali Jaffer Mohamed (Oman), Kathryn G. Dewey (USA). United Nations Agency Representatives: Cutberto Garza (UNU), Krishna Belbase (UNICEF). Advisory Group Maureen Black, Wm. Cameron Chumlea, Tim Cole, Edward Frongillo, Laurence Grummer-Strawn, Reynaldo Martorell, Roger Shrimpton, Jan Van den Broeck. For the work presented in this document, Huiqi Pan, Robert Rigby, Mikis Stasinopoulos and Stef van Buuren, participated in an advisory capacity. Participating countries and investigators Brazil: Cora Luiza Araújo, Cesar G. Victora, Elaine Albernaz, Elaine Tomasi, Rita de Cássia Fossati da Silveira, Gisele Nader (Departamento de Nutrição and Departamento de Medicina Social, Universidade Federal de Pelotas; and Núcleo de Pediatria and Escola de Psicologia, Universidade Católica de Pelotas). Ghana: Anna Lartey, William B. Owusu, Isabella Sagoe-Moses, Veronica Gomez, Charles Sagoe- Moses (Department of Nutrition and Food Science, University of Ghana; and Ghana Health Service). India: Nita Bhandari, Maharaj K. Bhan, Sunita Taneja, Temsunaro Rongsen, Jyotsna Chetia, Pooja Sharma, Rajiv Bahl (All India Institute of Medical Sciences). Norway: Gunn-Elin Aa. Bjoerneboe, Anne Baerug, Elisabeth Tufte, Kaare R. Norum, Karin Rudvin, Hilde Nysaether (Directorate of Health and Social Affairs; National Breastfeeding Centre, Rikshospitalet University Hospital; and Institute for Nutrition Research, University of Oslo). Oman: Ali Jaffer Mohamed, Deena Alasfoor, Nitya S. Prakash, Ruth M. Mabry, Hanadi Jamaan Al Rajab, Sahar Abdou Helmi (Ministry of Health). USA: Kathryn G. Dewey, Laurie A. Nommsen-Rivers, Roberta J. Cohen, M. Jane Heinig (University of California, Davis). iii - - Acknowledgements The WHO Child Growth Standards were constructed by the Coordinating Team in the Department of Nutrition for Health and Development of the World Health Organization. The Study Group is indebted to the parents, children and more than 200 field staff that participated in the WHO Multicentre Growth Reference Study. The generous contribution of many individuals that provided expertise and advice was also crucial to the development of the growth standards. The project has received funding from the Bill & Melinda Gates Foundation, the Netherlands Minister for Development Cooperation, the Norwegian Royal Ministry of Foreign Affairs, and the United States Department of Agriculture (USDA). Financial support was also provided by the Ministry of Health of Oman, the United States National Institutes of Health, the Brazilian Ministry of Health and Ministry of Science and Technology, the Canadian International Development Agency, the United Nations University, the Arab Gulf Fund for United Nations Development, the Office of the WHO Representative to India, and the Department of Child and Adolescent Health and Development. - iv - Contents Executive summary...........................................................................................................................xv 1. Introduction....................................................................................................................................1 2. Methodology..................................................................................................................................3 2.1 Design of the WHO Multicentre Growth Reference Study....................................................3 2.2 Anthropometry methods.........................................................................................................3 2.3 Sample description.................................................................................................................4 2.4 Data cleaning procedures and exclusions...............................................................................5 2.5 Statistical methods for constructing the growth curves..........................................................6 3. Construction of the head circumference-for-age standards...........................................................7 3.1 Indicator-specific methodology..............................................................................................7 3.2 Head circumference-for-age for boys.....................................................................................7 3.2.1 Sample size..................................................................................................................7 3.2.2 Model selection and results..........................................................................................7 3.2.3 WHO standards..........................................................................................................20 Charts.........................................................................................................................21 Tables.........................................................................................................................23 3.3 Head circumference-for-age for girls...................................................................................31 3.3.1 Sample size................................................................................................................31 3.3.2 Model selection and results........................................................................................31 3.3.3 WHO standards..........................................................................................................43 Charts.........................................................................................................................44 Tables.........................................................................................................................46 3.4 Comparisons between boys and girls...................................................................................54 3.4.1 WHO..........................................................................................................................55 4. Construction of the arm circumference-for-age standards...........................................................57 4.1 Indicator-specific methodology............................................................................................57 4.2 Arm circumference-for-age for boys....................................................................................57 4.2.1 Sample size................................................................................................................57 4.2.2 Model selection and results........................................................................................57 4.2.3 WHO standards..........................................................................................................72 Charts.........................................................................................................................73 Tables.........................................................................................................................75 4.3 Arm circumference-for-age for girls....................................................................................81 4.3.1 Sample size................................................................................................................81 4.3.2 Model selection and results........................................................................................81 4.3.3 WHO standards..........................................................................................................96 Charts.........................................................................................................................97 Tables.........................................................................................................................99 4.4 Comparisons between boys and girls.................................................................................105 4.4.1 WHO........................................................................................................................106 5. Construction of the triceps skinfold-for-age standards..............................................................107 5.1 Indicator-specific methodology..........................................................................................107 5.2 Triceps skinfold-for-age for boys.......................................................................................107 5.2.1 Sample size..............................................................................................................107 5.2.2 Model selection and results......................................................................................107 5.2.3 WHO standards........................................................................................................122 Charts.......................................................................................................................123 Tables.......................................................................................................................125 5.3 Triceps skinfold-for-age for girls.......................................................................................131 5.3.1 Sample size..............................................................................................................131 v - - 5.3.2 Model selection and results.....................................................................................131 5.3.3 WHO standards.......................................................................................................145 Charts......................................................................................................................146 Tables......................................................................................................................148 5.4 Comparisons between boys and girls................................................................................154 5.4.1 WHO.......................................................................................................................155 6. Construction of the subscapular skinfold-for-age standards.....................................................157 6.1 Indicator-specific methodology.........................................................................................157 6.2 Subscapular skinfold-for-age for boys..............................................................................157 6.2.1 Sample size..............................................................................................................157 6.2.2 Model selection and results.....................................................................................157 6.2.3 WHO standards.......................................................................................................172 Charts......................................................................................................................173 Tables......................................................................................................................175 6.3 Subscapular skinfold-for-age for girls...............................................................................181 6.3.1 Sample size..............................................................................................................181 6.3.2 Model selection and results.....................................................................................181 6.3.3 WHO standards.......................................................................................................198 Charts......................................................................................................................199 Tables......................................................................................................................201 6.4 Comparisons between boys and girls................................................................................207 6.4.1 WHO.......................................................................................................................208 7. Computation of centiles and z-scores for head circumference-for-age, arm circumference -for-age, triceps skinfold-for-age, subscapular skinfold-for-age...............................................209 8. Conclusion.................................................................................................................................213 9. Bibliography..............................................................................................................................215 Appendix A. Model specifications of the WHO child growth standards.......................................217 - vi - Figures Figure 1 Fitting of µ and σ curves of Model 1 for head circumference-for-age for boys (dotted line) and their respective sample estimates (points with solid line).....................9 Figure 2 Centile residuals from fitting Model 1 for head circumference-for-age from 0 to 24 months for boys...............................................................................................................10 Figure 3 Centile residuals from fitting Model 1 for head circumference-for-age from 24 to 71 months for boys...............................................................................................................10 Figure 4 Worm plots of z-scores for Model 1 for head circumference-for-age for boys..............11 Figure 5 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: head circumference-for-age for boys from birth to 24 months...............................................16 Figure 6 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: head circumference-for-age for boys from birth to 24 months................................................17 Figure 7 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: head circumference-for-age for boys from 24 to 71 months...................................................18 Figure 8 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: head circumference-for-age for boys from 24 to 71 months..................................................19 Figure 9 WHO head circumference-for-age z-scores for boys from birth to 60 months...............21 Figure 10 WHO head circumference -for-age percentiles for boys from birth to 60 months.........22 Figure 11 Fitting of the µ and σ curves of Model 1 for head circumference-for-age for girls (dotted line) and their respective sample estimates (points with solid line)...................33 Figure 12 Centile residuals from fitting Model 1 for head circumference-for-age from 0 to 24 months for girls...............................................................................................................34 Figure 13 Centile residuals from fitting Model 1 for head circumference-for-age from 24 to 71 months for girls...............................................................................................................34 Figure 14 Worm plots of z-scores for Model 1 for head circumference-for-age for girls...............37 Figure 15 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: head circumference-for-age for girls from birth to 24 months...............................................39 Figure 16 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: head circumference-for-age for girls from birth to 24 months................................................40 Figure 17 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: head circumference-for-age for girls from 24 to 71 months....................................................41 Figure 18 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: head circumference-for-age for girls from 24 to 71 months....................................................42 Figure 19 WHO head circumference-for-age z-scores for girls from birth to 60 months...............44 Figure 20 WHO head circumference-for-age percentiles for girls from birth to 60 months...........45 Figure 21 Comparison of boys' and girls' head circumference-for-age z-scores.............................55 Figure 22 Worm plots of z-scores for Model 1 for arm circumference-for-age for boys................59 Figure 23 Fitting of the µ, σ, and ν curves of Model 2 for arm circumference-for-age for boys from 3 to 71 months (dotted line) and their respective sample estimates (points with solid line)....................................................................................................62 Figure 24 Centile residuals from fitting Model 2 for arm circumference-for-age from 3 to 24 months for boys...............................................................................................................63 vii - - Figure 25 Centile residuals from fitting Model 2 for arm circumference-for-age from 24 to 71 months for boys..............................................................................................................63 Figure 26 Worm plots of z-scores for Model 2 for arm circumference-for-age for boys...............64 Figure 27 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: arm circumference-for-age for boys from 3 to 24 months.....................................................68 Figure 28 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: arm circumference-for-age for boys from 3 to 24 months.....................................................69 Figure 29 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: arm circumference-for-age for boys from 24 to 71 months...................................................70 Figure 30 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: arm circumference-for-age for boys from 24 to 71 months..................................................71 Figure 31 WHO arm circumference-for-age z-scores for boys from 3 to 60 months.....................73 Figure 32 WHO arm circumference-for-age percentiles for boys from 3 to 60 months.................74 Figure 33 Worm plots of z-scores for Model 1 for arm circumference-for-age for girls...............83 Figure 34 Fitting of the µ, σ, and ν curves of Model 2 for arm circumference-for-age for girls from 3 to 71 months (dotted line) and their respective sample estimates (points with solid line)....................................................................................................86 Figure 35 Centile residuals from fitting Model 2 for arm circumference-for-age from 3 to 24 months for girls..............................................................................................................87 Figure 36 Centile residuals from fitting Model 2 for arm circumference-for-age from 24 to 71 months for girls..............................................................................................................87 Figure 37 Worm plots of z-scores for Model 2 for arm circumference-for-age for girls...............88 Figure 38 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: arm circumference-for-age for girls from 3 to 24 months.....................................................92 Figure 39 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: arm circumference-for-age for girls from 3 to 24 months.....................................................93 Figure 40 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: arm circumference-for-age for girls from 24 to 71 months...................................................94 Figure 41 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: arm circumference-for-age for girls from 24 to 71 months..................................................95 Figure 42 WHO arm circumference-for-age z-scores for girls from 3 to 60 months.....................97 Figure 43 WHO arm circumference-for-age percentiles for girls from 3 to 60 months.................98 Figure 44 Comparison of boys' and girls' arm circumference-for-age z-scores...........................106 Figure 45 Worm plots of z-scores for Model 1 for triceps skinfold-for-age for boys..................109 Figure 46 Fitting of the µ, σ, and ν curves of Model 2 for triceps skinfold-for-age for boys from 3 to 71 months (dotted line) and their respective sample estimates (points with solid line)..............................................................................................................112 Figure 47 Centile residuals from fitting Model 2 for triceps skinfold-for-age from 3 to 24 months for boys............................................................................................................113 Figure 48 Centile residuals from fitting Model 2 for triceps skinfold-for-age from 24 to 71 months for boys............................................................................................................113 Figure 49 Worm plots of z-scores for Model 2 for triceps skinfold-for-age for boys..................114 - viii - Figure 50 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: triceps skinfold-for-age for boys from 3 to 24 months.............................................................118 Figure 51 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: triceps skinfold-for-age for boys from 3 to 24 months.............................................................119 Figure 52 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: triceps skinfold-for-age for boys from 24 to 71 months...........................................................120 Figure 53 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: triceps skinfold-for-age for boys from 24 to 71 months...........................................................121 Figure 54 WHO triceps skinfold-for-age z-scores for boys from 3 to 60 months.........................123 Figure 55 WHO triceps skinfold-for-age percentiles for boys from 3 to 60 months.....................124 Figure 56 Worm plots of z-scores for Model 1 for triceps skinfold-for-age for girls...................133 Figure 57 Fitting of the µ, σ, and ν curves of Model 2 for triceps skinfold-for-age for girls from 3 to 71 months (dotted line) and their respective sample estimates (points with solid line)..............................................................................................................135 Figure 58 Centile residuals from fitting Model 2 for triceps skinfold-for-age from 3 to 24 months for girls.............................................................................................................136 Figure 59 Centile residuals from fitting Model 2 for triceps skinfold-for-age from 24 to 71 months for girls.............................................................................................................136 Figure 60 Worm plots of z-scores for Model 2 for triceps skinfold-for-age for girls...................137 Figure 61 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: triceps skinfold-for-age for girls from 3 to 24 months.............................................................141 Figure 62 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: triceps skinfold-for-age for girls from 3 to 24 months.............................................................142 Figure 63 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: triceps skinfold-for-age for girls from 24 to 71 months...........................................................143 Figure 64 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: triceps skinfold-for-age for girls from 24 to 71 months..........................................................144 Figure 65 WHO triceps skinfold-for-age z-scores for girls from 3 to 60 months.........................146 Figure 66 WHO triceps skinfold-for-age percentiles for girls from 3 to 60 months.....................147 Figure 67 Comparison of boys' and girls' triceps skinfold-for-age z-scores.................................155 Figure 68 Worm plots of z-scores for Model 1 for subscapular skinfold-for-age for boys...........159 Figure 69 Fitting of the µ, σ, and ν curves of Model 2 for subscapular skinfold-for-age for boys from 3 to 71 months (dotted line) and their respective sample estimates (points with solid line)..................................................................................................162 Figure 70 Centile residuals from fitting Model 2 for subscapular skinfold-for-age from 3 to 24 months for boys.................................................................................................163 Figure 71 Centile residuals from fitting Model 2 for subscapular skinfold-for-age from 24 to 71 months for boys...............................................................................................163 Figure 72 Worm plots of z-scores for Model 2 for subscapular skinfold-for-age for boys...........164 Figure 73 3rd, 10th, 50th, 90th, 97th smoothed centile curves and empirical values: subscapular skinfold-for-age for boys from 3 to 24 months.............................................................168 Figure 74 5th, 25th, 50th, 75th, 95th smoothed centile curves and empirical values: subscapular skinfold-for-age for boys from 3 to 24 months............................................................169 ix - -