In this week's Lancet (sorry figure not included, otherwise full text here)
M Sachs, PhD 

The Lancet 2006; 368:1868-1869 

Will the new WHO growth references do more harm than good?
Colin Binns  a   and   MiKyung Lee a 

Exclusive breastfeeding for 6 months is the normal way to feed all infants. 
The new WHO growth reference released in April, 2006, is based on breastfed 
infants under optimum conditions.1 The sample is highly selected for the 
factors likely to promote growth in breastfed infants, and less than 10% of 
those initially surveyed were included in the final study. 

Most mothers and health professionals are concerned about their infants' 
growth, particularly for the first 6 months. If they believe their infants 
are not growing adequately, they are more likely to introduce supplementary 
foods, including “top-ups” with infant formula or even switching to formula 
completely. “Insufficient milk” is the most common reason for the early 
cessation of breastfeeding and mothers often self-diagnose this on the basis 
of perceived slower growth. 

The new WHO growth references show the maximum growth rates that can be 
achieved with breastfeeding under optimum conditions. But, for the first 6 
months of life, the new WHO growth references, for boys and girls, are 
heavier than those produced by the US National Center for Health Statistics 
(which formed the basis of the old WHO references) for every Z score from 
−3 to +3 (see figure).2 The difference is greater for weights below 
the mean, and it is in this region of the chart that mothers are more likely 
to be anxious about the growth of their infant. 


Figure. Comparison of weight-for-age Z scores for boys
Z scores −3 (bottom pair of lines) to +3 (top pair of lines) shown. 
Solid lines=new reference. Dashed lines=old reference. Reproduced from 
reference 2, with permission. 

The new WHO growth reference is a triumph of modern statistical techniques. 
But has the real purpose been lost in the technology? What is really needed 
is a growth reference that presents growth rates that can be realistically 
achieved during the first 6 months of life and maximises the duration of 
exclusive breastfeeding. 

We declare that we have no conflict of interest. 

References
1. de Onis M, Garza C, Onyango AW, Martorell R. The WHO Multicentre Growth 
Reference Study: planning, study design, and methodology. Acta Paediatr 
2006; 450 (suppl): S5-S96. 

2. WHO. WHO child growth standards: methods and development. Geneva: World 
Health Organization, 2006:
http://www.who.int/childgrowth/publications/technical_r...
(accessed Nov 7, 2006). 

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