New WHO Growth Standards: more harm than good?

Summary of published letter¹

A recent letter in the LANCET questions whether the new WHO growth standards,² reported in issue 28 of Field Exchange, may do more harm than good. The authors argue that most mothers and health professionals are concerned about their infant's growth, particularly for the first six 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. It is further argued that '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 standards show the maximum growth rates that can be achieved with breastfeeding under optimum conditions. But, for the first six months of life, the new WHO growth standard weights, for boys and girls, are heavier than those produced by the NCHS (National Centre for Health Statistics) for every Z score from -3 to +3. 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 infants.

The authors state that the new WHO growth standards are a triumph of modern statistical technique but go on to ask whether the real purpose has been lost in technology. They conclude that what is really needed is a growth reference that presents growth rates that can be realistically achieved during the first six months of life, and maximises the duration of exclusive breastfeeding.

¹ Binns. C and Lee.M (2006). Will the new WHO growth references do more harm than good? The Lancet, volume 368, Nov 2006

² www.who.int/childgrowth/en