The joy of having a child with Down syndrome

Growth charts are essential items in the paediatric toolkit. Using the wrong chart for the job can impact adversely on children’s health, at both population and individual level. In this issue of Acta Pædiatrica, Cole et al. (1) present a growth reference based on breastfed babies: why is this contribution so important? Almost twenty-five years ago Waterlow and Thomson speculated that “growth faltering” at about 3 mo of age amongst breastfed babies reflected inadequacy of energy supply (2). We now recognize that this problem was more apparent than real and was largely attributable to the use of an inappropriate norm, the old National Centre for Health Statistics (NCHS) growth reference compiled from measurements of artificially fed American infants from the 1920s onwards. Amongst the earliest to highlight this problem was the Cambridge group, which found that although breastfed Gambian infants were smaller than Cambridge infants, the weight trajectories of the two groups were remarkably similar when expressed as a percentage of the reference mean weight-for-age. The apparent “faltering” actually reflected a tendency for breastfed babies to show accelerated growth in the early months of life. In other words, the pattern portrayed by the international reference and many other charts did not reflect the growth of breastfed babies in privileged and resourcepoor countries alike (3). Qualitatively similar observations have since been made on breastfed infants in numerous locations (4), creating consensus that a new infant growth reference is needed (5). Although now widely acknowledged amongst the scientific community, this phenomenon is still not universally recognized by either health workers or parents. They tend to worry when an infant’s growth appears to slow down at about 3 mo of age. The charts published in this issue are important because they offer an immediate, simple and practical solution to this common problem. They are derived from longitudinal monthly weight measurements of a group of British infants breastfed for at least the first 24 wk of life and can conveniently be used along with other charts widely used in the United Kingdom, based on the UK 1990 growth reference (6) (both charts are available from the Child Growth Foundation, 2 Mayfield Avenue, London W14 1PW. cgflondon@aol.com). In fact, the differences between the “breastfed” chart and the standard UK chart are not large, partly because the Cambridge infant growth study data formed a significant proportion of infant measurements used in compiling the UK 1990 reference. They amount on average to 0.3 standard deviations, equating to a potential fall between 8 wk and 52 wk of just less than one centile space (0.66 standard deviations, SD). The principle is nevertheless important for two reasons. First, it focuses health workers’ attention on the issue and reminds us that growth of the breastfed infant represents a biological norm correlated with optimal health outcomes. Secondly, it allows health workers to account more objectively for the effect of breastfeeding when trying clinically to unravel the effects of many variables on an infant’s growth pattern. How valid is the new chart for clinical use? Cole et al. comment on this, pointing out that the Cambridge data fell close to the median of seven other series from a number of industrialized countries (4). This is reassuring, but it may be worth noting that the potential for early rapid growth or subsequent slowing down could be greater than depicted. Whereas the Cambridge data ranged between 0.5 SD above and 0.3 SD below the NCHS mean, the extremes observed in two different studies exceeded the mean by as much as 0.9 SD in either direction. This emphasizes the case for a new international reference based on the growth of large numbers of exclusively breastfed infants, such as that being developed by the World Health Organization (5). How relevant are the data in the contemporary policy context encouraging complementary feeding from “. about 6-months”? The age at which these Cambridge infants received solid foods (15.4 4.1 weeks, mean SD) may seem early, though in fact it was relatively late when the study was conducted: in 1985 62% of mothers nationally introduced their infants to solids by 3 mo of age and 90% by 4 mo of age (7). However, the effect of complementary feeding age is unlikely to be large. Available data from controlled studies suggest that introduction at 4-mo rather than 6mo does not affect growth rate, which was also the conclusion of a recent major systematic review (8). It may cause compensatory reduction in breast-milk intake (9), although even this effect seems small and less important than the introduction of formula (10). Finally, how do we explain these differences between formula-fed and breastfed babies? A number of physiological mechanisms have been proposed ranging