To the Editor: Growth charts are important tools in assessing the physical development of infants and children. Understanding and comparing the derivation and applicability of the new World Health Organization Child Growth Standards1 and the Centers for Disease Control and Prevention (CDC) growth charts2 is essential.

Arguments for and against the standard use of the new WHO growth charts are being discussed on the basis of differences in study designs used and growth patterns found.3,4 The WHO charts show the growth of breastfed infants on the basis of data from about 8500 children from widely different ethnic backgrounds and cultural settings (Brazil, Ghana, India, Norway, Oman and the United States); these children were from selected populations in which no health, environmental or economic constraints on growth existed.1 In contrast, the CDC charts represent the combined growth pattern of artificial-formula-fed and breastfed infants in the United States, where about 50% of infants are never breastfed and only around 33% are breastfed for 3 months or longer.2

Is it possible to misdiagnose breastfed infants who are growing normally as failing to thrive if the CDC growth charts are used? The simplest common definitions used for failure to thrive are a drop below the 3rd or 5th percentile for weight, or when growth deviates from an established growth curve for 3 consecutive months.5 By the CDC growth charts, the normal growth pattern described by the WHO Child Growth Standards for a 15th percentile, breastfed, female infant at 18 months would meet all three definitions of failure to thrive. The clinical response to this perceived failure to thrive may be to provide additional energy in the form of energy-dense foods or supplements (eg, artificial formula). This would at best be unnecessary, and at worst might contribute to the development of overweight and obesity.

So, where to from here? We recommend that all health professionals who use growth charts be cognisant of which chart they are using and its application, especially for breastfed infants. There is also a need for Australian national and state governments to debate which growth charts should be used and in what contexts. Finally, irrespective of the choice of growth charts, it must be recognised by practitioners and the general public that these charts are guides only, and should be used as part of a holistic approach to infant growth assessment and management.