Royal College of Paediatrics and Child Health An Introduction to the new UK-WHO Growth Charts

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An Introduction to the new UK-WHO Growth Charts

© 2009 Royal College of Paediatrics and Child Health www.growthcharts.rcpch.ac.uk © 2009 Royal College of Paediatrics and Child Health www.growthcharts.rcpch.ac.uk

Why did the WHO think we needed new charts?

• Differences in weight gain seen between breast fed infants and charts

• Healthy breast fed infants show very similar growth patterns around the world

• Decided to produce charts that set breast feeding as the norm

• For use worldwide


WHO Charts - development

• 15 year programme of planning, data collection and analysis

• Sampled breast fed infants of non-smoking non-deprived mothers in 6 countries (USA, Norway, India, Ghana, Brazil, Oman) birth to 5 years

• Very similar growth patterns in all 6 centres

• Charts are a description of optimal rather than average growth

• Suitable for all children


UK-WHO Charts – development

• SACN (scientific advisory committee on Nutrition) recommended:

– Adoption of WHO charts in UK from age 2 weeks

– Continue to use UK birth and preterm data …

• No preterm data in WHO

• Good match between UK birth data and WHO at 2 weeks

• RCPCH commissioned to design charts and produce educational materials

• Design and instructions developed by expert group and tested in focus groups of staff and parents


UK-WHO Charts - implementation

• Launch date for charts plus supporting materials May 2009 (England)

– A4

– 6 PCHR charts (3 pages)

– Low birth weight chart 23 weeks gestation to 2 years

• Use for all new births

• No need to re-plot for older children

• Continue to use UK 1990 for older children (4 years+)

32 weeks gestation to 4 years


Effect on growth patterns of change to WHO standard

Weight

• Charts now allow for neonatal weight loss

– Average children no longer drop down chart between birth and 4 weeks

• After first 6 months:

– Drop in % below lower centiles and % weight faltering.

– Rise in % above upper centiles for weight.

Height

• Very similar growth in height /length at all ages


Comparison of WHO and UK90

Boys

1

3

5

7

9

11

13

15

0 13 26 39 52

Age in weeks

Wei

gh

t

WHO blackUK 1990 red

By 12 months, WHO 2nd centile = UK1990 0.4th


How will the new charts be different?

• Separate preterm section

• Head circumference extended to 2 years

• Length /height discontinuity

• Evidence based instructions

• No 4-18 section (yet)


New chart features

No lines between birth and 2 weeks

Term birth measurements plotted at age 0

Preterm births plotted on preterm section


Why no lines between birth and 2 weeks?

• Birth weight charts do not naturally join infancy chart

– Weight at 2 weeks of age not = birth weight at 42 weeks gestation

• New charts use UK 1990 data at birth, then WHO data from 2 weeks

• Between birth and 2 weeks most infants lose and regain weight and charts cannot allow for this

• Gap emphasises importance of looking at weight gain relative to birth weight in first days, not centile position


De-emphasised 50th centile

• Avoids confusing messages to parents about perceived ‘need’ for all children to be on 50th centile

– Centile labels at both ends of each curve

– 50th centile identifiable from location of curve label


Age labelling

• Age errors are the most common source of plotting mistakes

• Charts marked in both weeks and calendar months


Length - height discontinuity

• Centile lines shift down slightly at age 2

• New charts show length up to age 2 years and height from age 2 onwards

• Due to spinal compression, when a child is measured standing they are slightly shorter than when lying down

• Important not to let length to height transition cause worries for parents

• What matters is whether the child continues to follow their new centile position after the transition


Personal child health record charts

• Fewer pages in total

• Fold-out measurement recording page: allows plotting while in view

• Information aimed at parents developed via focus groups


A4 Instructions and interpretation aids (and HV instruction leaflet)• Draws on available research evidence

• Clear guidance on measuring and plotting

• Role of length and height measures

• Measurement frequency

• Defines range of normality and need for further assessment, but not what action to be taken

© 2009 Royal College of Paediatrics and Child Health www.growthcharts.rcpch.ac.uk

UK-WHO Charts Summary

• Launched in England from May 2009 for all new births • To be used in Scotland for all babies born on or after 1 January

2010 • New UK-WHO Charts are a description of optimal rather than

average growth so weight gain patterns will appear different• New charts show premature birth weight and infancy growth

separately; all infants from 37 weeks gestation should be plotted at term (age 0)

• De-emphasised 50th centile, but identifiable from location of curve label

• A4 charts include detailed instructions; PCHR has information aimed at Parents


Measuring and plotting

Summary: Measurement

• Weighing:– Use only class III electronic scales– Weigh babies naked, children over two in vest and pants,

without shoes

• Head circumference– Use narrow, paper or plastic tape round widest part of the

head

• Length (up to age 2) – Proper equipment essential (length board or mat)– Measurers should be trained– Shoes and nappy removed

• Height (after age 2)– Rigid rule with T piece, or stadiometer– Shoes removed


Measuring and plotting

Summary: Plotting and Centiles

• Record measurement and date in ink• Plot in pencil• Age errors are commonest source of plotting mistakes• Centiles describes the percentage expected to be

below that line • A child is

– on a centile if within ¼ space of line, – between the two centiles if not

• A centile space is the distance between two centile lines

© 2009 Royal College of Paediatrics and Child Health www.growthcharts.rcpch.ac.uk © 2009 Royal College of Paediatrics and Child Health wwwgrowthcharts.rcpch.ac.uk

New born infants

Summary

• Plot birthweight at age 0 for all infants born 37+ weeks,

• Weigh within first week as part of the assessment of feeding as early weighing …

does not discourage breast-feeders

allows timely identification of feeding problems

• Assess early weight gain relative to birthweight … recovery of birthweight by 2 weeks suggests that feeding is

effective and that the child is well

if large weight loss at any time, or still below birthweight at 2 weeks, calculate % weight loss

• 10% weight loss needs careful assessment


Plotting pre-term infants

Summary

• Preterm = birth before 37 weeks completed weeks gestation

• Infants born before 32 weeks, plus any sick neonate, should be plotted on low birth weight chart

• Well preterm infants born after 32 weeks should be plotted in preterm section until 42 weeks gestation

• Then plot on the 0–1 year chart using arrow drawn back method of gestational correction

• Continue gestational correction till 12-24 months


Infants and toddlers

What is a normal rate of growth?

• Measure length or height whenever concerned about weight gain or growth

• Measurements commonly show wide variation

– If worried measure on a few occasions

– Healthy children usually show a stable general pattern over time

• What is a normal rate of head growth?

– Head circumference usually tracks within one centile space

– Fewer than 1% of infants drop or rise through >2 centile spaces after the first few weeks

Should be carefully assessed



Adult height prediction

• Plot the most recent height

• Find corresponding centile on the adult scale

• Four out of five children will be within 6cm of this value when an adult

For example: if a child is on the 75th centile for height, the Adult Height Predictor suggests they may reach an Adult Height of 181cm +/- 6cm

+/-

6cm



When should a single measurement trigger assessment?

• There is no single threshold below or above which a child’s weight or height is definitely abnormal

• Further assess …

All children with measurements below 0.4th centile

Child with height above 99.6th centile plus other concerns

• If weight above 99.6th centile after age 2, lookup BMI centile



Body Mass Index (BMI) lookup

BMI = 91st

• Read off the weight and height centiles from the growth chart.

• Plot the weight centile (left axis) against the height centile (bottom axis)

• Read off the corresponding BMI centile from the slanting lines.

• Record centile with date in the data box

• Accurate to ¼ centile space


Reference list

• De Onis M, Garza C, Victora CG, Onyango AW, Frongillo EA, Martines J. 2004. The WHO Multicentre Growth Reference Study: planning, study design, and methodology. Food Nutr Bull 25(1):S15-S26.

• Department of Health. Application of the WHO Growth Standards in the UK. Department of health . 2007. Department of Health. http://www.sacn.gov.uk/

• WHO multicentre growth reference study group. 2006. Assessment of differences in linear growth among populations in the WHO Multicentre Growth Reference Study. Acta Paediatr Suppl 450:56-65.

• Wright C, Lakshman R, Emmett P, Ong KK. 2008. Implications of adopting the WHO 2006 Child Growth Standard in the UK: two prospective cohort studies. Arch Dis Child 93(7):566-9.

• Wright CM, Parkinson KN. 2004. Postnatal weight loss in term infants: what is normal and do growth charts allow for it? Arch Dis Child Fetal Neonatal Ed 89 (3): F254-F257.

Documents

Royal College of Paediatrics and Child Health An Introduction to the new UK-WHO Growth Charts