The WHO Multicentre Growth Reference

Study(1997-2003)

WHO Growth Reference StudyPrescriptive Approach

Optimal Nutrition– Breastfed infants– Appropriate complementary feeding

Optimal Environment– No microbiological contamination– No smoking

Optimal Health Care– Immunization– Pediatric routines

OptimalGrowth

MGRS study design

year 1 year 2 year 3

Longitudinal (0-24 months)

Cross-sectional (18-71 mo)

Eligibility Criteria for IndividualsNo health, environmental or economic constraints on growth• Mother willing to follow feeding recommendations:

Exclusive/ predominant breast feeding for 1st 4 mths, introduction of complementary feeding by 6 mths

• Term, single birth• Lack of significant perinatal morbidity• Non smoking mothers before and after delivery

MGRS Study Design and Sample

MGRS Study Design and Sample

Longitudinal study (birth-24 months)• Mothers & newborns screened & enrolled at birth• Weight, length, head circumference: 21 times

over 24 months• Arm circumference: 10 times between 3 and 12

months• Skin fold thickness : 6 times between 14 and 24

months

MGRS Study Design and Sample

Cross-sectional survey (18-71 mo) Weight, length, head circumference, arm

circumference, skin fold thicknessTotal sample 8440 children from 6 countries• 300 newborns per site (1743 total) followed up till

24 mo from the longitudinal study• 1400 children per site (6647 total) aged 18-71 mo

through the cross sectional surveys

Construction of growth curves

• The rigorous methods of data collection yielded very high-quality dataset

• State-of-art statistical methods applied in a methodical way:

– Detailed examination of 30 existing methods, including types of

distributions and smoothing techniques;

– Selection of a software package flexible enough to allow

comparative testing of alternative methods and the actual

generation of the curves;

– Systematic application of the selected approach to the data to

generate models that resulted in the best fit

WHO Child Growth Standards• Attained growth

• Weight-for-age• Length/height-for-age• Weight-for-length/height• Body mass index-for-age• Mid-upper arm circumference-for-age• Triceps skinfold-for-age• Subscapular skinfold-for- age• Head circumference-for-age

• Growth velocity• Weight• Length/height• Head circumference• Arm circumference

Comparison of existing growth charts

Data charact

Source

Study period

Population

Age-group

CDC

Multiple different studies

1963-1994

US, mixed feeding, no racial/ethnic diff

Birth-20 yrs

WHO

Primary data

1997-2003

6 Countries pooled data. healthy breastfed children

Birth-5yrs

WHO standards versus NCHS reference Important differences that vary by age group, sex, growth

indicator, specific percentile or z-score curve, and the nutritional status of index populations.

Differences are particularly important during infancy due to type of feeding and issues related to study design (eg, measurement interval)

Difference in shapes of the weight-based curves in early infancy makes interpretation of growth performance strikingly different depending on whether the WHO standard or the NCHS reference is used

Healthy breastfed infants track along the WHO weight-for-age mean z-score while appearing to falter in NCHS from 2 months onwards – implications assessment of lactation performance and adequacy of infant feeding

Mean weight-for-age z-score

-0.8

-0.4

0

0.4

0.8

0 1 2 3 4 5 6 7 8 9 10 11 12

Age (months)

CDC

NCHS

MGRS

Mean weight-for-age z-scores of healthy breastfed infants relative to the NCHS, CDC and WHO curves

Comparison of WHO with NCHS and CDC chart

Prevalence of stunting (below -2 SD length/height-for-age) by age based on the WHO standards and the NCHS reference in Bangladesh

0

10

20

30

40

50

60

70

80

0-5 6-11 12-23 24-35 36-47 48-60 0-60

Age (months)

%NCHS WHO

Prevalence of underweight (below -2 SD weight-for-age) by age based on the WHO standards and the NCHS reference in Bangladesh

0

10

20

30

40

50

60

70

80

0-5 6-11 12-23 24-35 36-47 48-60 0-60

Age (months)

%NCHS WHO

Growth charts

• Consist of a series of percentile curves that illustrate the distribution of selected body measurements in the study population

• Used to track the growth of children from infancy thru adolescence

• Indicates the state of the child's health, nutrition and well being

References: 

1.World Health Organization. WHO child growth standards: length/height-for-age, weight-for-length, weight for height, and body mass index for age: methods & development. Geneva. World Health Organization. 2006

2.World Health Organization. Physical Status: The use and interpretation of anthropometry. WHO Technical Report Series 854. Geneva. World Health Organization; 1995. P. 418, 422-23.

3.Cole TJ. The use and construction of anthropometric growth reference standards. Nutrition Research Reviews,1993(6):19-50

4. Mercedes O, Ray Y. The WHO Growth Chart: Historical consideration and current scientific issues. Bibl Nutr Dieta;1996(53):pp 74-89

5. Onis M, Onyango AW, Borghi1 E, Garza C and Yang H. Comparison of the World Health Organization (WHO) Child Growth Standards and the National Center for Health Statistics/WHO international growth reference: implications for child health programmes. Public Health Nutrition,2006;9(7):942–947