Implications of adopting the WHO 2006 Child Growth Standard in the UK: two prospective cohort studies
- 1Division of Developmental Medicine, University of Glasgow, Glasgow, UK
- 2MRC Epidemiology Unit, Cambridge, UK
- 3Community based Medicine, University of Bristol, Bristol, UK
- 4Department of Paediatrics, University of Cambridge, Cambridge, UK
- Dr K K Ong, MRC Group Leader & Paediatric Endocrinologist, MRC Epidemiology Unit, Institute of Metabolic Science, Addenbrooke’s Hospital, Box 285, Cambridge CB2 0QQ, UK;
- Accepted 16 September 2007
- Published Online First 1 October 2007
Background: The WHO 2006 Child Growth Standard is based on data from international optimally nourished breastfed infants from birth to age 5 years.
Objective: To assess the potential effect of its use on weight and growth monitoring of UK children.
Participants: Full-term members of two population-based UK birth cohorts: the Children in Focus sub-cohort of the Avon Longitudinal Study of Parents and Children (ALSPAC) (n = 1335) and the Gateshead Millennium Baby Study (GMS; n = 923).
Design: Growth data from birth to 5 years were converted into z-scores relative to the WHO 2006 standard.
Results: Compared with the WHO standard, both UK cohorts had higher birth weights (mean z-scores: GMS, 0.17; ALSPAC, 0.34) and ALSPAC had higher birth lengths. After birth, length showed a good fit at all ages. By 2–4 months, both cohorts were similar in weight to the WHO median (mean WHO weight z-score at 4 months: GMS, 0.01; ALSPAC, −0.07), but thereafter the UK cohorts were heavier (mean WHO weight z-score at 12 months: GMS, 0.57; ALSPAC, 0.65). At age 12 months, the risk of being classified as underweight (weight <2nd centile) was considerably lower according to the WHO standard than by the UK 1990 Growth Reference (RR = 0.15, 95% CI = 0.07 to 0.32), and the risk of being classified as obese at 4–5 years (body mass index >98th centile) was slightly increased (RR = 1.35, 95% CI = 1.02 to 1.78).
Conclusions: Adoption of the WHO 2006 Growth Charts would set a markedly lower standard of weight gain beyond the age of 4 months for UK infants and could support efforts to avoid future childhood obesity. However, the WHO standard is not representative of size at birth in the UK.
Funding: UK Medical Research Council, the Wellcome Trust and the University of Bristol provide core provide support for ALSPAC. The infancy phase of the GMS was funded by the Henry Smith Charity, SPARKS, Northern and Yorkshire NHS R&D and Gateshead NHS R&D.
Competing interests: None.