CDC Growth Charts

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					Reference Population: Standard Normal Curve

                     50th Percentile




        5th                            95th
 Indicators of Nutritional Status
Head circumference-for-age    <5th percentile
                             >95th percentile

Stunting/shortness
 length or height-for-age     <5th percentile

Underweight
 weight-for-length
                               <5th percentile
 BMI-for-age
 Indicators of Nutritional Status


Overweight
Weight-for-length         >95th percentile
BMI-for-age


Risk of overweight
                     85th to 95th percentile
 BMI-for-age
   Reference Data Sets: Birth to 36 Months
    Head Circum


      Length




          Weight


Weight-for-Length

                    B   3      6   9      12    15 18      21   24   27   30   33 36
                                          Age in Months

          MO/WI Natality               National Natality         PedNSS
          Fels                         NHANES III ('88-'94)      NHANES II ('76-'79)
          NHANES I ('71-'74)
        Reference Data Sets: 2 to 20 Years

   Stature




Weight/BMI



                 2       4       6        8     10    12      14    16    18    20
                                     Age in Years

             NHANES III ('88-'94)       NHANES II ('76-'79)        NHANES I ('71-'74)

             HES III ('66-'70)          HES II ('63-'65)
Exclusions from the Reference Data

 • VLBW infants (<1500 g) were excluded
   because they have different growth
   patterns


 • NHANES III weight data for 6+ year olds
   were excluded to avoid an upward shift
   in weight and BMI-for-age curves
        Age-Adjusted Prevalence of
    Overweight* From NHANES I to III1

                                    NHANES I    II   III

        20

        15

        10

         5

         0
             Boys 6-11 y Boys 12-17 y Girls 6-11 y Girls 12-17 y

                           Sex and Age Group

*>95th percentile BMI-for-age
1 Troiano et al, Arch Pediatr Adolesc Med 1995: 149: 1085-1091.
     CDC Growth Charts Are for All
   Racial and Ethnic Groups Combined

• The effect of race and ethnicity on growth is
  controversial
• Inadequate sample data for racial- and ethnic-
  specific charts
• Environmental influences appear to contribute
  to variations in growth but more research is
  needed
Age Adjusted Prevalence of Low Height-for-Age
by Ethnic Groups, Children Aged 0 to 5 Years1
      15




      10
                                                          White
                                                          Asian
       5




       0
           79 80 81 82 83 84 85 86 87 88 89 90 91 92 93

                            Year of Visit
 1   Yip and Mei, 1995
 Breast-Fed vs. Formula-Fed Infants

• Mode of infant feeding can influence growth

• New charts represent the combined growth
  patterns of breast-fed and formula-fed infants

• Separate charts are not recommended

• Working group of the World Health Organization
  (WHO) is collecting data on infants following the
  WHO feeding recommendations to develop charts
  for infants and children through age 5.
                                    Disjunction: Smoothed in New Charts
                      120
                                                                                       120

                      110                                                          110
                                        Old                                                         New
                      100
Length/height in cm




                                                                                       100




                                                                 Length/height in cm
                       90
                                                                                       90

                       80
                                                                                        80

                       70
                                                                                        70

                       60                                                              60

                       50                                                              50

                       40
                            0   6   12 18 24 30 36 42 48 54 60                         40
                                                                                         0   6   12 18 24 30 36 42 48 54 60
                                           Age in month                                                  Age in month
Reference Population for CDC Growth Charts


       • Racially and ethnically diverse

       • Birth to 36 months:
         nationally representative

       • Breast-fed and formula-fed infants
New Reference Curves Compared with Old Curves*
       Prevalence of Nutrition Indicators

 Birth to 36 Months
   Nutrition Indicator       Change in Prevalence

 Stunting/shortness          2% to 4% lower from 6-24 mos
 length-for-age <5th
 Underweight                 3% to 5% higher
 weight-for-length <5th
 Overweight                  Same
 weight-for-length >95th

 * NHANES III, PedNSS, WHO
New Reference Curves Compared with Old Curves*
       Prevalence of Nutrition Indicators
 Children 2 to 5 years of age

 Nutrition Indicator                 Change in Prevalence

 Stunting/shortness                     2% to 3% lower
 height-for-age <5

  Underweight** <5                      3% to 5% higher


  Overweight** 95th                     3% to 5% higher

 * NHANES III, PedNSS, WHO
 **BMI-for-age, weight-for-stature
New in the CDC Growth Charts

 Charts extend to 20 years

 3rd and 97th percentiles available

 Lower limits of length (45 vs. 49 cm) and
  height (77 vs. 90 cm) extended

 BMI-for-age charts (2-20 years) added

 85th percentile (at risk of overweight)
  added
              What Is BMI?

• Body mass index (BMI) =
          weight (kg)/height (m)2

• BMI is an effective screening tool; it is not a
  diagnostic tool

• For children, BMI is age and gender specific,
  so BMI-for-age is the measure used
  Advantages of BMI-for-Age

 Provides a reference for adolescents that
 was not previously available

 Consistent with adult standards so can be
 used continuously from 2 years of age to
 adulthood

 Tracks childhood overweight into
 adulthood
    Tracking BMI-for-Age from Birth to 18 Years with
Percent of Overweight Children who Are Obese at Age 251


                       100               BMI < 85th                 BMI >=85th                 BMI >=95th
                                                                                                       83
                                                                                                                     77
        % obese as adults


                            80                                                                    75
                                                                                        69                      67
                            60                                           52        55


                            40                                      36
                                                       26
                                 16 17            19
                            20               15                12             11             10             9

                            0
                                  Birth       1 to 3            3 to 6      6 to 10          10 to 15       15 to 18
                                                            Age of child (years)

  Whitaker et al. NEJM: 1997;337:869-873
   Advantages of BMI-for-Age

 BMI-for-age relates to health risks

   Correlates with clinical risk factors for
    cardiovascular disease including hyperlipidemia,
    elevated insulin, and high blood pressure

   BMI-for-age during pubescence is related to
    lipid levels and high blood pressure in middle
    age
BMI-for-Age Compares Well with


• Weight-for-stature measurements

• Measures of body fat
         Why Use BMI-for-Age?
• Recommended by expert committees to
  evaluate overweight

  Guidelines   for Overweight in Adolescent Preventive
       Services (Am J Clin Nutr 1994;59:307-316)
     Obesity Evaluation and Treatment: Expert Committee
       Recommendations (Pediatrics 1998 Sept;(102)3:e 29)
     Assessment of Childhood and Adolescent Obesity:
       International Obesity Task Force (Am J Clin Nutr 1999,
       70,suppl)
         Shape of Growth Curves:
   Weight-for-Stature versus BMI-for-Age

              35                                          35
                                            95th
                                                                                       95th
              30                                          30
                                             50th
Weight (kg)




              25
                                             5th
                                                          25
                                                                                       50th




                                                    BMI
              20
              15                                          20                            5th
              10
                                                          15
              5
              0                                           10
                   80   90    100 110 120 130                  24   72   120 168 216
                             Stature (cm)                           Age (months)
      For Children, BMI Differs by Age
BMI                         BMI



      Boys: 2 to 20 years
                                  Example: 95th
                                  Percentile Tracking

                                  Age      BMI

                                  2 yrs    19.3
                                  4 yrs    17.8
                                  9 yrs    21.0
                                  13 yrs   25.1


BMI                         BMI
                                  Shape of BMI-for-
BMI


      Boys: 2 to 20 years
                            BMI
                                  Age Growth Curve:
                                  “Adiposity” Rebound
                                  (AR)

                                    Example: Early AR

                                     Age (mos)    BMI
                                      26         18.2
                                      32         17.4
                                      38         18.5
                                      41         18.7


BMI                         BMI
BMI
   BMI-for-Age Cutoffs

> 95th percentile   Overweight

85th to < 95th      Risk of overweight
 percentile

< 5th percentile    Underweight
         Performance of BMI-for-Age
            as a Screening Tool

• Using the 85th and 95th percentiles as cut points,
  few children are incorrectly identified as over-fat
  but some over-fat children will be missed.

• It is desirable to correctly identify those children
  not at risk of overweight or overweight.
Can you see risk?

                                              • This boy is 3 years, 3 weeks old.
                                              • Is his BMI-for-age

                                                  - below the 5th percentile?
                                                  - 5th to <85th percentile: normal?
                                                  - >85th to <95th percentile: at risk
                                                          for overweight?
                                                  - >95th percentile: overweight?


Photo from UC Berkeley Longitudinal Study, 1973
            Plotted BMI-for-Age
BMI                         BMI
                                  Measurements:
      Boys: 2 to 20 years
                                  Age=3 y 3 wks
                                  Height=100.8 cm
                                         (39.7 in)
                                  Weight=18.6 kg
                                         (41 lb)
                                  BMI=18.3
                                  BMI-for-age=
                                       >95th percentile
                                       overweight
BMI                         BMI
Can you see risk?

                                                   • This girl is 4 years, 4 weeks old.
                                                   • Is her BMI-for-age

                                                      - below the 5th percentile?
                                                      - 5th to <85th percentile: normal?
                                                      - >85th to <95th percentile: at
                                                              risk for overweight?
                                                      - >95th percentile: overweight?


 Photo from UC Berkeley Longitudinal Study, 1974
              Plotted BMI-for-Age

BMI                          BMI
                                   Measurements:
      Girls: 2 to 20 years          Age= 4 y 4 wks
                                    Height=106.4 cm
                                    (41.9 in)
                                    Weight=15.7 kg
                                    (34.5 lb)
                                    BMI=13.9
                                    BMI-for-age=
                                         10th percentile
                                         Normal
BMI                          BMI
Can you see risk?

                                                  • This girl is 4 years old.
                                                  • Is her BMI-for-age

                                                    - below the 5th percentile?
                                                    - 5th to <85th percentile: normal?
                                                    - >85th to <95th percentile: at
                                                           risk for overweight?
                                                    - >95th percentile: overweight?


Photo from UC Berkeley Longitudinal Study, 1973
             Plotted BMI-for-Age
BMI                          BMI
                                   Measurements:
                                   Age=4 y
      Girls: 2 to 20 years
                                   Height=99.2 cm
                                         (39.2 in)
                                   Weight=17.55 kg
                                          (38.6 lb)
                                   BMI=17.8
                                   BMI-for-age=
                                        94thpercentile

BMI                          BMI        At risk for
                                   overweight
  Accurate Measurements are Critical

                                  5 1/2 year old boy
BMI                         BMI



      Boys: 2 to 20 years
                                  Weight: 41.5 lb
                                  Height: 43 in
                                  BMI= 15.8
                                  BMI-for-age=50th %tile
                                  Inaccurate height
                                  measurement: 42.25
                                  BMI=16.3
BMI                         BMI   BMI-for-age=75th %tile
Summary of Using BMI-for-Age

• BMI-for-age is the recommended method
  for screening overweight and underweight
• For children, BMI is age and gender
  specific; for adults there are fixed cut
  points
• Accurate and periodic measurements are
  important elements of any anthropometric
  screening
Available CDC Growth Charts

   •   Birth to 36 months
        Weight-for-length

        Length-for-age

        Weight-for-age

        Head circumference-for-age
Available CDC Growth Charts

     •   2 to 20 years
          BMI-for-age

          Stature-for-age

          Weight-for-age

      Weight-for-height
Steps to Plot BMI-for-Age

• Select appropriate growth chart
• Record data
• Obtain accurate weight and height
  measurements
• Calculate BMI
• Plot measurements
• Interpret plotted measurements
    Case Study: “Sam”

•   Name: Sam
•   Weight: 37 lb 4 oz (16.9 kg)
•   Height: 41.5 inches (105 cm)
•   DOB (date of birth): 9/15/1994
•   DOV (date of visit): 4/4/1998
       Data Entry Table for BMI-for-Age

 Mother’s Height________
                                             Gestational
 Father’s Height________
                                             Age________ Weeks

Date      Age          Weight      Height     BMI          Comment

4/4/98                37 lb 4 oz   41.5 in
Calculating BMI with the Metric System
       Formula: weight (kg)/[height (m)]2

  Calculation: [weight (kg)/ height (cm)/
                      height (cm)] x 10,000


  Example: A child’s weight=16.9 kg and height=105.4 cm

  BMI = [16.9 kg / 105.4 cm / 105.4 cm] x 10,000 = 15.2
  Calculating BMI with the English System

  Formula: weight (lb)/[height (in)]2 x 703

Calculation: [weight (lb)/height (in)/height (in)] x 703


   Example: A child’s weight = 37 pounds, 4 ounces and
             height = 41 1/2 inches
            (convert fractions to decimal value)

   BMI = [37.25 lb / 41.5 in / 41.5 in] x 703 = 15.2
       Data Entry Table for BMI-for-Age

 Mother’s Height________
                                             Gestational
 Father’s Height________
                                             Age________ Weeks

Date      Age          Weight      Height     BMI          Comment

4/4/98    3 1/2       37 lb 4 oz   41.5 in    15.2
Sam’s BMI Plotted on Boy’s BMI-for-Age Chart
  BMI                         BMI



        Boys: 2 to 20 years         Interpretation:
                                    • Sam’s BMI-for-age is
                                    slightly below the 25th
                                    %tile so it falls within
                                    the normal range.
                                    • Of 100 boys who are
                                    the same age, fewer than
                                    25 have a BMI-for-age
                                    lower than Sam’s.



  BMI                         BMI
   BMI-for-Age Cutoffs

> 95th percentile   Overweight

85th to < 95th      Risk of overweight
 percentile

< 5th percentile    Underweight
Interpreting the BMI-for-Age Chart
 • BMI-for-age indicates a child’s weight in
   relation to his/her height for a specific age
   and gender

 • Need a series of BMI plots to determine
   the growth trend

 • If indices deviate from normal growth
   patterns, further assessment may be
   needed
Future Directions for CDC Training

 • Continuation of training at national
   meetings
 • Development of a Web-based training
   module
 • Training focus: accurate weighing and
   measuring, calculating BMI, plotting
   and interpreting the growth charts
Distribution of CDC Growth Charts


          Electronic Copies

 http://www.cdc.gov/growthcharts/

				
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