Jul 3, 1990 - Queensland and 3Department of Demography, Australian National University, ... Cherbourg Aboriginal Settlement is in southeast Queensland.
J. faediatr. Child Health (1990) 26, 192-196
The changing growth of Aboriginal children A. E. DUGDALE’, I. A. MUSGRAVEZ and K. STREATFIELD3
Human Nutrition Research Group, Department of Child Health, University of Queensland, 2Queensland Department of Health, Charlotte Street, Brisbane. Queensland and 3Department of Demography, Australian National University, Canberra, Australian Capital Territory, Australia
Abstract We have used data from children at an Aboriginal settlement in Queensland to demonstrate the changing patterns of growth over the last 30 years. In cohorts of children born during the early 1950s and 1960s the mean weight-for-age value was satisfactory for the first three months of life, but then fell until aged 12 months and remained at about 92% of the NCHS median value until 5 years old. In the cohort born in 1972-73 there was some improvement and in the 1982-83 cohort the mean weight-for-age value was close to international levels from 1 to 5 years. The decline in weight-for-age between 3 and 12 months was still present. Length-for-age values were not available in the 1950s and 1960s but the mean value increased from the 1972-73 cohort to the 1982-83 cohort, which was close to international levels. The mean weight-for-length was close to international levels in the 1972-73 cohort, but in the 1982-83 cohort was high from 3 to 12 months and then fell close to the international level. These data indicate that the children at this Aboriginal settlement are now growing satisfactorily. The impaired growth between 3 and 12 months needs further investigation, but most of the earlier concerns about poor growth appear to have been resolved. Key words:
Aboriginal; child; growth; secular changes.
The growth of infants and children is widely used as an indicator of their health and nutrition. There is evidence that some diseases, particularly gastroenteritis, have a higher incidence and are more severe in undernourished~hi1dren.l.~ The growth of children is also used as an indirect indicator of the wellbeing of the whole community. The most commonly used growth indicator is weight-for-age which is compared with local, national or internationaldata sets. The World Health Organization (WHO) has recommended that the American National Center for Health Statistics (NCHS) data set be used as an international reference, as it has been shown that children of all ethnic groups approach this level of growth when they come from upper class, healthy and well-nourished fa mi lie^.^,^ Ethnic differences in growth are much smaller than those due to disease and malnutrition. Weight-for-age remains the most useful single indicator of nutritional status, but interpretation is complicated as two separate factors contribute to its level. Waterlow has based a classification of nutrition on the observation that early and prolonged undernutrition leads to stunting, and this deficit can seldom be regained even if later nutrition is good.6 In such a stunted child a bodyweight below the reference level can indicate satisfactory current nutrition and health. A child who is presently malnourished is thin, and this is best measured by his weight-for-length. When this child is refed. weight-forlength returns to normal, but if the undernutrition has been prolonged, the height-for-agewill remain low. It is the strength and weakness of weight-for-age that it reflects both acute malnutrition and the long-term effects of stunting. There are many reports that Aboriginal infants tend to have lower birthweights than the general Australian community (see
Correspondence: A. E. Dugdale. Human Nutrition Research Group, Department of Child Health, University of Queensland. St Lucia. Qld 4067, Australia. Accepted for publication 3 July 1990.
Thomson for a survey of results7). Infants tend to grow for the first few months, but then their growth S I O W SThis . ~ - pattern ~~ is typical of children in developing countries. In this paper we report the changes in growth of children from birth to 5 years over a 30-year period at Cherbourg Aboriginal Settlement.
MATERIALS AND METHODS Cherbourg Aboriginal Settlement is in southeast Queensland about 270 km from Brisbane. There are approximately 1500 people living on the settlement, all of Aboriginal or part-Aboriginal descent. Over the last 30 years the standard of housing and facilities have improved considerably and now resemble welfare housing elsewhere in Queensland. There is a 40-bed hospital with a staff of registered nurses. For many years there has been a visiting doctor, but for the past 5 years there have been resident doctors. There is also an infant health clinic on the settlement and a health team, run by the Aboriginal Health Programme, visits from time to time. There were two sources of data: (1) With very few exceptions, all infants born andlor living on the settlement visited the infant health clinic. Many visited first before the age of 2 weeks and then continued to visit until the age of 5 years. The data collected on each visit included the weight of the child, the type of feeding and any intercurrent illnesses. From 1972 onwards the length of the child was also measured at 3, 6, 9, 12, 24, 36, 48 and 60 months. To identify any changes in growth we have taken data from all the records at the clinic of infants who were born in the years 1952-53, 1962-63, 1972-73 and 1982-83. The data were the weights and lengths at the visit closest to 3, 6, 9, 12, 24, 36, 48 and 60 months where these data were available. Most visits were within a month of the set age. After 1972 lengths were measured up to the age of 2 years and heights in older
193
Changinggrowth of Aborginal children
children. To avoid confusion, the measurement is referred to as length throughout this paper. (2) The second source of data was the records of the Aboriginal Health Programme. From 1972 teams who had been trained and equipped to do accurate anthropometric measurements visited the settlement from time to time. They examined, weighed and measured children who presented themselves, but this was a minority of all children and the times that the teams visited did not coincide with the ages of the clinic measurements.
between boys and girls so the data from the two sexes have been combined. The Gomez categories of %W/A have been used to find the number of severely malnourished ~ h i l d r e n The . ~ cut-off levels for these categories are greater than 90% of the ‘standard’ - normal; 75-89% Grade 1 or mild malnutrition; 60-740/0 Grade 2 or moderate malnutritionand less than 60% Grade 3 or severe malnutrition. The t-test has been used to test differences between growth of different cohorts. In Figs 1-3, a logarithmic time base has been used on the x-axis to avoid crowding of changes in growth status that occurred in the first year of life.
Methods of analysis A computer program was written to analyse the data. The date of birth, sex of the child and date of examination were entered. The computer calculated the exact age and then using WHOlNCHS tables for the 50th percentile values of weight-forage-for-sex and length-for-age-for-sex,calculated the expected weight and height for that exact age. The percentage weightfor-age (OhW/A) and length-for-age(%UA) were then calculated. This was done for each examination on each child. Percentage weight-for-length (%W/L) was also calculated from the WHOlNCHS data set. There was no significant difference
RESULTS Comparisons between data from the clinic and the health programme. The Aboriginal Health Programme data was collected from 1972 onwards by nurses and health assistants who had been trained in the techniques of measuring and recording growth data. They were equipped with Harpenden stadiometers (vertical and
Table 1 The changes in weight-for-age of Aboriginal children at Cherbourg over three decades. The mean weight-for-age of each cohort at each age is expressed as a percentage of the median of the NCHS data set. The percentages of children less than 75%, less than 60% and greater than 120% of the NCHS median are also given Birth
3112
91 103.2 15.10
100 100.9 14.21
6112
9112
12/12
24/12
36/12
48112
60112
98 92.6 9.72
93 91.9 9.03
89 90.4 9.53
94 90.3 9.77
1952-53 n = 119
n
mean s.d. Oo/
< 75%
YO< 60%
> 120%
o/o
1962-63 = 109
n
n
mean s.d.
< 75% < 60% > 120%
016
Oh
o/o
1972-73 n = 132
n
mean s.d. O h < 75% 010
120%
o/o
3 0 12
91 100.0 17.12 6 1 12
I23 97.1 15.51 5 1 7
3 0 10
87 100.6 18.04 10 1 14
93 101.2 14.49 1 1 11
101
96.1 13.32
101
93.1 11.36
4 0 4
5
88 97.8 15.06
85 94.7 14.08
5 0 7
5 0 4
95 98.7 12.14 1
0 5
0 2
92 95.0 12.43 4 1 1
100
91.1 9.45 4 0 0
93 91.7 11.74
5 0 0
2 0 0
91 92.9 10.92
84 91.8 10.22
2
7 0 2
0 0
2 0 0
102 95.5 14.5
1 03 96.3 14.65
102 94.5 10.21
5 0 3
2
1
0
0 3
2
7 0 0
87 91.2 10.56 5 0 0
92 93.9 10.70 3 0 1
2 0 0
81 91 .I 10.62 6 0 1
94 94.0 11.48 4 0 2
1982-83 n mean s.d.
n = 121
< 75%
103 97.5 17.14
YO< 6OVo
11 1
> 120%
10
O/o
o/o
89 104.5 14.58 2 0 10
92 101.7 13.00 2 0 5
86 100.5 13.30
89 98.3 11.92
86 101.1
10.83
87 98.8 10.58
83 98.5 12.04
80 100.2 14.78
1
1
0
0
0
0
0 5
0 3
0 7
0 2
0 5
0 4
A. E.Dugdale e?al.
194
horizontal) and beam balance scales. All this equipment was checked regularly with standard weights and measures. Their measurements were therefore accurate but the coverage was low and the examinations irregular. Where examinations by the clinic and the health team were done within 1 month of each other we compared the percentage weight-for-age, percentage length-for-age and percentage weight-for-length to detect significant differences. In no instance did the two measurements put the child in a different nutritional grade, nor was there any systematic bias which would alter the mean values. Results based on the clinic measurements therefore give a reliable picture of the growth of the children. We also checked the data to see whether there was a difference in growth between boys and girls. From birth to 2 years there were no significant differences in the %W/A of boys and girls, but after that age girls tended to have a higher %W/A than boys, although this difference was not statistically significant. %L/A and O/oW/L showed no trends or significant differences. The probabilities were >>0.05.
WEIGHT FOR AGE OF CHILDREN AUSTRALIAN NW L MRC DATA ABORIGINAL 1952-53 s--. ABORIGINAL 1962-83 o...... o ABORIGINAL 1972-73 A.-& ABORIGINAL 1982-83 0-0 0-0
9 ,lo[ Y
0
6
9
12
24
36 4 8 60
AGE IN MONTHS
Fig. 1 Changes in the weight-for-ageof Aboriginal children at Cherbourg. The weight-for-age is expressed as a percentage of the median of the NCHS data set. The mean values for Australian children in the NH&MRC data set are also shown.
Changes in weight-for-age over the 30-year period
(P>>0.05). The results of the 1972-73 cohort were significantly greater than for the 1962-63 cohort at 12 and 24 months, but the results of the 1982-83 cohort differed significantly from those in the 1972-73 cohort at 9 months and from 2 years onwards (PcO.05 for all). Table 1 also shows the percentage of children in the lower Gomez grades of nutrition. Even in the 1952-53 cohort there were no children in the high-risk Grade 3 level. In later years there was only an occasional child in Grade 3 and the number in Grade 2 (*y?;yzw..o
*
L-!-b
I:/
e 9
............... o...'
,;
g 100
6
'.
..o
gO "
a
0
3t
6
9
12
24
36 4 8 60
AGE IN MONTHS
Fig. 2 Changes in height-for-age (weight-for-age)of Aboriginal children at Cherbourg. The mean values of the NH8MRC data set are also shown.
Fig. 3 Changes in the weight-for-length (weight-for-height)of Aboriginal children at Cherbourg. The mean values for the NHBMRC data set are also shown.
had not biassed the results. The lengths-for-age up to 12 months tended to be lower in the 1982-83 cohorts than in the 1972-73 cohort but these differences were not significant. From 2 years onwards the %L/A were significantly greater in the 1982-83 cohort than in the 1972-73 cohort. At all ages the Australian length-for-age was very close to the WHO/NCHS reference level. The opposite trend was seen in the weights-for-length (see Table 3 and Fig. 3). From 3 to 9 months, the %W/L showed that the children were significantly plumper in the 1982-83 cohort than in the 1972-73, but from 2 years onwards there was a trend for the children to have lower weights-for-length,although this did not reach statistical significance. At all ages the weights-for-lengthof Australian children on the median of the NH&MRC data set were well above the WHOlNCHS reference level.
cohort showed increased growth and the 1982-83 cohort had weights-for-ageclose to the international reference level. These improvements occurred in spite of a continuing pattern of poor growth between the ages of 3 and 12 months. Analysis of the Aboriginal growth data presented by Kettle and Gracey eta/. showed the same pattern of delayed growth from 3 to 12 months.8z'0 The growth of the children in those studies, as measured by %W/A, remained low throughout childhood. The growth of white Australian children in the NH&MRC data set did not have this decline in relative weight-for-age in the first year of life, but the data of Hitchcockera/. showed that amongst white infants in Perth, there was a slight tendency for %W/A to drop between 3 and 12 months but thereafter %W/A remained close to the international reference level.'2 This pattern of growth may be associated with breast feeding of infants. It is possible that the WHOlNCHS data set, which is based on American data, was inappropriate for Australian conditions at that time and that the fall in the %W/A from 3 to 12 months reflects this mismatch. Figure 1 shows the NH&MRC data based on the general Australian population of children. The pattern of %W/A of the NH&MRC series, based on children in NSW, shows a very different pattern to the Aboriginal data. In the NH&MRC data there is rise in the %W/A from birth to 3 months, but then the mean value remains almost stationary and well above the WHOlNCHS reference level. The pattern of a downward slide across the percentiles from 3 to 12 months' is therefore not a general Australian problem, but is related in some way to the ethnicity, or more likely the environment, of the Aboriginal children.
DISCUSSION
In any study of secular changes retrospective data must be used, even though these data were recorded contemporaneously with the events. The main problems arising from retrospective data are the completeness of the data set and the accuracy of the measurements. The steps taken in this report show that these factors do not invalidate the results. The data show large increases in the growth achievement of Aboriginal children at Cherbourg Settlement from the 1952-53 cohort to the 1982-83 cohort. There was no change in the %W/A from 1952-53 to the 1962-63 cohorts, but the 1972-73
A. E. Dugdale eta/.
196
Infant mortality has decreased at Cherbourg and other Aboriginal settlements, but infections probably remain more common among Aboriginal infant^.'^-'^ During the first year of life infants are weaned and also come into increasing contact with contaminants and infections. These would reduce both food intake and growth at this age. However, it has been reported from Guatemala that nutritional status can improve without improvements in health.I6 Even in the 1950s and 1960s when infant mortality rates at Cherbourg were high, almost none of the infants on the settlement had weights-for-age below 60% of the reference levels which are known from overseas studies to be associated with high mortality One result of the change in the growth achievements is the increase in the numbers of children over 120% of the reference level for weightfor-age. The mean level of weight-for-ageis very close to 100°/o of the international norm so this higher level of weight-for-age may indicate that taller children are heavier. Nevertheless, this may indicate a future problem of obesity and should be monitored. Adult obesity and associated diseases are already problems among Aborigines, but the relationshipof early nutrition with adult obesity and degenerative diseases is not altogether clear.20.21 We have no early data on the length of the children, but by 1972-73,the weight-for-lengthof that cohort was at or above the WHOlNCHS reference level and only slightly below the Australian NH&MRC level. The increasing weight-for-age but stationary weight-for-lengthbetween the 1972-73 and 1982-83 cohorts is explained by the increase in the heights of the children over the decade. From the age of 2 years there had been a significant increase in the length-for-age over the decade, so that the lengths of the 1982-83 cohort was almost the same as the reference level and close to that of the Australian children on the median of the NH&MRC data set. If growth status gives an indication of the health and nutrition of children, then the large changes in growth at Cherbourg Settlement over the last 30 years indicate marked improvement in health. This growth of these children is now close to, or for some indicators, above the international reference level and this suggests that most of the health and nutritional problems of early childhood have been controlled. There are several possible explanations for these changes in growth and health. Cherbourg is only a few kilometres from a country town and has easy access to Brisbane, so has become more ‘integrated’ into the general Australian culture than more remote communities. The reduction in the birth rate, with greater spacing of pregnancies and fewer very young mothers are perhaps more important factors. We are now analysing the available data to evaluate these factors. However, the continuing pattern of decline in growth between the ages of 3 and 12 months needs further investigation. Although we cannot relax our efforts to maintain and improve the health and growth of children, we could well
shitt research emphasis to the health of adults, where lifestyle diseases are causing excessive morbidity and early death.
ACKNOWLEDGEMENTS This study was supported by funds from the NH&MRC of Australia and the Australian National University. We thank the Chairman and the Cherbourg Community Council for permission to use these data.
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