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A guide to the UK-WHO child growth charts

Alison Wall
MSc BSc HV SCM SRN FP Cert
Health Visitor/Child Protection Lead
West Hertfordshire Primary Care Trust

In 2007, the Scientific Advisory Committee on Nutrition (SACN) and the Royal College of Paediatrics and Child Health (RCPCH) recommended the use of World Health Organization (WHO) standard child growth charts in the UK.1 These new charts became available for use from 11 May 2009. Provider organisations are ordering the new materials and setting up training programmes to ensure that the charts are used to a high standard by all those health professionals who work with children.

Adoption of the WHO standard charts
The 1990 UK reference charts, which were in use for over 40 years, were based on cohorts of formula-fed and mixed-fed infants. The old reference graphs demonstrated the growth of babies, rather than how they should grow. In contrast, the new UK-WHO standard charts set an optimal level to be achieved and are preferable to using charts based on a mix of feeding from both breast and bottle.

The charts are the fruit of 16 years' work collecting and analysing growth data. They are based on research data from 8,440 healthy breastfed infants from Brazil, Ghana, India, Norway, Oman and the USA.2 The babies were selected from a cohort of exclusively breastfed babies for six months, with some continuing with breastfeeding into their second year. The babies were chosen from nonsmoking families.

The data are valuable as they reflect growth patterns across five continents and include babies nurtured under optimal conditions. It is interesting that, despite differing geographical regions, they all had similar linear growth curves. This shows that, given similar favourable conditions, children from different regions across the globe have the potential to grow at a similar rate. Most of the current evidence suggests that babies who follow the pattern of growth laid down in the new charts will have a reduced risk of obesity later in life.

The new UK-WHO charts were initiated as the result of intensive work by the WHO in 1997. Their aim was to develop a new international standard for assessing the physical growth, nutritional status and motor development of children from birth to five years. The project work for the UK has been led by Professor Charlotte Wright from Glasgow University and funded by the Department of Health.

Differences between the growth charts
The new UK-WHO charts are standard charts in preference to reference charts, and combine UK 90 and WHO data. They illustrate how babies should grow and use a prescriptive rather than descriptive approach, detailing average growth outcomes. The new chart packs contain:

  • An A4 chart from 0–4 years (including a section for premature infants born from 32–37 weeks).
  • An adult height predictor.
  • A body mass index (BMI) conversion chart.
  • Information for parents and carers.
  • A neonatal chart for babies born from 23 weeks' gestation.
  • A "Windows of Achievement" for six key motor developmental milestones, thereby aligning motor development alongside physical development.

These new charts will be included in the Personal Child Health Record (PCHR or "Red Book"). Generally, there is little change in the pattern of weight gain between two weeks and six months. However, after six months there are significant differences, as UK babies tend to gain more weight. Twice as many children on the WHO chart compared to the 1990 chart are now above the 98th centile, whereas about 1% are below the second centile. Height and length ratios show a close match at all ages.

The new charts have no centiles between birth and two weeks of age. The reason for this is that users are encouraged to measure ratios of weight loss according to birth weight rather than centile position. This is a more accurate reflection of the physiological process that takes place at this time. A normal percentage weight loss would be about 10% of birth weight from birth to 10 days.

Impact of new standards on growth monitoring and public health
The new charts will ensure that growth based on breastfeeding will be viewed as the norm. Information for parents should help them to understand that it is not necessarily healthy for babies to climb up and across centile curves. It is important that parents and carers understand the relevance of growth curves for the future wellbeing of their children. With the appropriate training and support, the new charts should help in the challenge to reduce the increasing rise of both childhood and adult obesity.

Issues to consider
Although there are no centiles between birth and two weeks because of the difficulties with interpreting growth at this time, there is a danger that poor and inadequate nutrition could be missed. This period is a critical time for breastfeeding to start to become established, with the baby fixing on the breast correctly and draining the milk available. If problems are not detected at this time and the mother and baby are not seen frequently, there is the danger that a baby may receive insufficient nourishment.

There is also an issue about the impact on those mothers who choose to formula feed. Data show that, initially, about 60% of mothers breastfeed, but that by four months only 25% are still doing so.3 This means that for these infants, growth patterns will be assessed against a standard that is not being realised.

Training and educational materials
The national drive to update skills will reduce the risk of inadequately trained child health professionals. The RCPCH has started a programme of "training the trainers" and has produced materials that are available online.4 The question of who measures and who interprets the data is an important area of debate. If measurements are incorrectly collected, they will then be incorrectly interpreted. This debate is of high importance, particularly at this time of restraint in budget allocations and capacity issues.

Benchmarks
For the first time, public health messages and public health tools are being brought together in the area of growth monitoring. The new charts, with their accompanying training materials, should help to prioritise the importance of such monitoring in assessing the health and wellbeing of babies and young children. This will provide a good foundation for ongoing good practice so that the same messages are continued throughout childhood and into adolescence.

Standards set benchmarks, and the new charts will help to inform global public policy initiatives. The charts are comprehensive and consist of more than just weight, height and circumference measurements; the child will be assessed for their BMI, which should help in efforts to reduce childhood obesity. Growth and wellbeing will be monitored alongside general developmental skills, particularly motor skills.
Premature growth patterns will be accurately monitored using the specialist preterm charts. Information about the importance of growth measurement and its link to general health and wellbeing should be conveyed to parents and carers so that public health professionals can work in partnership with parents.

Carer empowerment is also a key principle to develop in public health practice, and this can only be achieved through information and greater mutual understanding. The new standards will aid the diagnosis of unhealthy trends in infant nutrition and provide evidence of the need for public health interventions.

Conclusion
It was recommended that the new WHO charts be used from May 2009 for all new births, but that older children should not be reviewed against these new standards; for these children, the existing UK 1990 charts should continue to be used for the present.

The move to standardise growth measurement should facilitate the communication of the correct messages about infant development, and enable public health practitioners to share a meaningful discourse about growth trends with carers and other health professionals.

References
1. Scientific Advisory Committee on Nutrition, Royal College of Paediatrics and Child Health. Application of the WHO Growth Standards in the UK. Norwich: Stationery Office; 2007.
2. Department of Health, Royal College of Paediatrics and Child Health, World Health Organization. UK-WHO Growth Charts 0–4 years. London: Royal College of Paediatrics and Child Health; 2009.
3. Hamlyn B, Brooker S, Oleinikova K, Wands S. Infant Feeding 2000. London: The Stationery Office; 2002.
4. Royal College of Paediatrics and Child Health. UK-WHO Growth Charts: Early Years. Available from: www.rcpch.ac.uk/Research/UK-WHO-Growth-Charts

Resources
World Health Organization
The WHO Child Growth Standards
W: www.who.int/childgrowth/en/

Royal College of Paediatrics and Child Health
UK-WHO Growth Charts: Early Years
W: www.rcpch.ac.uk/Research/UK-WHO-Growth-Charts