Why the new WHO growth charts are dangerous to breastfeeding.
|Abstract:||Keywords: complementary foods, exclusive breastfeeding, growth reference, infant growth, World Health Organization|
Lee, Mi Kyung
|Publication:||Name: Breastfeeding Review Publisher: Australian Breastfeeding Association Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2008 Australian Breastfeeding Association ISSN: 0729-2759|
|Issue:||Date: Nov, 2008 Source Volume: 16 Source Issue: 3|
There are many reasons to ensure that all infants have the benefit of breastfeeding. The increased morbidity and mortality in infants fed artificial baby milk have been extensively documented (Binns & Davidson 2003; WHO Collaborative Study Team on the Role of Breastfeeding on the Prevention of Infant Mortality 2000). Australia is currently experiencing an epidemic of obesity and overweight which will have a significant impact on the future health of our population. Given the known impact of early growth on subsequent health and body composition, early feeding is of considerable public health interest.
In a large cohort study from Finland, Eriksson and colleagues (2001)
found that children, whose growth was faster in height, weight and body mass index from birth to seven years of age, were more likely to develop obesity later in life. There have now been several meta-analyses that have analysed the role of an infant's diet and, in particular, the effect of breastfeeding on reducing the subsequent risk of obesity (Harder et al 2005; Owen et al 2005a; Owen et al 2005b).
Cattaneo (2006), in his report for the European Union, described four systematic reviews which have included 340,000 subjects from a total of 48 papers, all of which have been observational studies. Observational studies must be used for research on breastfeeding because it would be completely unethical and experimentally very difficult to undertake a randomized controlled trial. The review by Cattaneo (2006) concluded that breastfeeding has a definite protective effect against the development of obesity (odds ratio 0.8, CI 0.68-0.93). While the odds ratio may be small, the preventable fraction, or population attributable risk, is very large because of the high prevalence of breastfeeding in the community. The size of the effect depends on the exclusivity and the duration of breastfeeding. The accumulation of evidence, even though it is primarily from observational studies, is more than sufficient justification to implement a major public health promotion campaign for breastfeeding.
While infant feeding methods influence growth, it is also true that infant growth can have an effect on feeding method. The use of an infant growth chart and the regular monitoring of growth is the most widely used paediatric intervention around the world. Parents and health care professionals use adequate growth as the most important way of assessing the adequacy of breastfeeding. When the weight of an infant falls below the 5th percentile (or even the 10th percentile) on the growth chart it is often a cue for a mother to introduce complementary feeds or to cease breastfeeding altogether. Mothers commonly report insufficient breastmilk or insufficient infant growth as a reason for introducing artificial feeds (Binns & Scott 2002) or premature weaning (James 2004).
Regular assessment of growth is recommended in the Australian Dietary Guidelines for Children (National Health and Medical Research Council 2003). Regular measurement and plotting against a growth reference is an important monitoring tool as parents often do not recognise the rate of growth or being overweight in themselves or their children (Jeffery et al 2005). Practical experience shows that health professionals frequently do not recognise underweight, on casual examination, often assuming that the child is younger than they actually are.
The term growth reference refers to the set of data used to compile a growth chart. Reference implies that the growth chart is used as a record to plot the individual child's growth over time and that the trend in growth is more important than the absolute position on the chart. However, on occasion, health professionals have to rely on a single measurement point as previous records may not be available at the time of consultation and advice may be given based upon one consultation. In 1978, the World Health Organization (WHO) adopted the growth reference produced by the US National Centre for Health Statistics (NCHS) (Hamill et al 1979) for international use (WHO 1978). These growth references were later adopted by the NHMRC for use in Australia (Binns 1985). These charts have been included in personal health records in Australia and many other countries for use by parents and health workers as an ongoing record of a child's growth and development.
In 2000, the US charts were revised to eliminate some minor anomalies around two years of age (Kuczmarski et al 2000). In particular, the data used for infants was updated and the calculation of some percentiles was revised. The international growth reference was derived from a mix of infants who were breastfed and artificially-fed.
It was known for some years that exclusively breastfed babies grow at a slightly lower rate than the reference (Dewey 1998), although if the charts are used as a reference (and not as a standard) the difference was not all that important. De Onis, Garza and Habicht (1997) expressed concerns about the existing growth reference:
These concerns led to the development of a new growth reference by WHO (WHO Multicentre Growth Reference Study Group 2006). The details of the development process have been described in great detail (de Onis et al 2004; WHO 2006). After a decade of work the WHO published their results, with the following description: The new standards adopt a fundamentally prescriptive approach designed to describe how all children should grow rather than the more limited goal of describing how children grew at a specified time and place (de Onis et al 2007). Previously WHO has used the term reference, but now feels confident enough about the new growth study to refer to it as a standard.
However, in the new growth study, WHO used a sample that was highly selective for the factors likely to promote growth in breastfed infants. Infants were from higher socioeconomic groups and were free of any illness. The final cohort studied comprised fewer than 5% of those initially surveyed (WHO 2006). There were no children included in the sample from any of the mongoloid races, despite the fact that they make up one quarter of the world's population.
When compared to the NCHS and CDC 2000 references, the new WHO reference is heavier for the first six months of life. This point is shown in the weight-for-age comparisons in Figure 1 (de Onis et al 2007; WHO 2006). The example shown is for boys, but the trend in the growth reference is similar for girls. After six months of age, the new WHO reference trends lower than the older references, reflecting the fact that by 12 months breastfed infants are leaner than their artificially-fed cousins. As a result of using the new, heavier WHO reference under the age of six months, an increased number of infants will fall below the percentile lines usually used to assess adequacy of growth, a point acknowledge by WHO and the Royal College of Physicians (de Onis et al 2007; SACN/RCPCH Expert Group on Growth Standards 2007). For example, in Australia approximately 7% more infants at three months of age will fall below the 10th percentile. The exact proportion of infants falling into this category will depend on age and the overall nutritional status of the population being studied. If these mothers are concerned about their infant's growth and give up exclusive breastfeeding, then a significant number of babies may be exposed to unnecessary complementary or supplementary feeds.
After a decade of planning and development, WHO have produced a growth reference that does not meet the need expressed by de Onis, Garza and Habicht in 1997. Their concern at that time was that the existing growth reference was too high and might lead mothers to introduce complementary foods unnecessarily (de Onis, Garza & Habicht 1997). Rather than conceding that WHO got it wrong for the first six months of an infants life, she now appears to be arguing that it doesn't matter (de Onis & Onyango 2008).
But breastfeeding does matter and the choice of a growth reference for monitoring infant growth is important. Any other intervention that could affect the life and health of children (such as a new vaccine) would have been subjected to a randomised controlled trial. Yet no such trial has been undertaken and WHO is still recommending that the new growth reference be introduced. If this happens, it is our opinion that the likely effect will be an increase in complementary feeds, a reduction in exclusively breastfeeding rates and possibly a decline in overall breastfeeding.
Breastfeeding is critical to infant health and its beneficial effects persist into adulthood. Exclusive breastfeeding to six months remains the key factor in the health of Australian children and the campaign against obesity and should be actively promoted to all mothers. A growth chart is designed to be used as a reference with serial measurements that indicate continuing growth being more important than the percentile location of any one isolated measurement. Prior to any replacement of charts in Australia, there needs to be a growth study that includes a randomised controlled trial of the new WHO growth chart to determine whether there is likely to be undesirable consequences to rates and duration of breastfeeding. In the meantime, we recommend that the new WHO growth reference should not be used below the age of six months because of its potential impact on breastfeeding rates.
[FIGURE 1 OMITTED]
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Colin Binns, Jennifer James and Mi Kyung Lee
Prof Colin Binns
School of Public Health
GPO Box U1987
Perth, Western Australia 6845
Telephone +61 8 9266 2952
Fax +61 8 9266 2958
the NCHS curves are inappropriate for healthy, breastfed infants. Recent research shows that infants fed according to recommendations by the WHO and who live under conditions that favour the achievement of genetic growth potentials grow less rapidly than, and deviate significantly from, the NCHS reference. The negative deviations are large enough to lead health workers to make faulty decisions regarding the adequate growth of breastfed infants, and thus to mistakenly advise mothers to supplement unnecessarily or to stop breastfeeding altogether. Given the health and nutritional benefits of breastfeeding, this potential misinterpretation of the growth pattern of healthy breastfed infants has great public health significance. The premature introduction of complementary foods can have life-threatening consequences for young infants in many settings, especially where breastfeeding's role in preventing severe infectious morbidity is crucial to child survival.
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