Nutrition and Health, 2000, Vol. 14, pp. 77 87 0260-1060/00 $10

c 2000 A B Academic Publishers. Printed in Great Britain

LOW BIRTHWEIGHT IN ELECTORAL WARDS: A USEFUL HEALTH AND SOCIAL INDICATOR AT LOCAL LEVEL

MARGARET WYNN AND ARTHUR WYNN

9 View Road, Highgate, London N6 4DJ, UK

ABSTRACT

Greater use of electoral ward data is recommended for the guidance of allocation of resources to reduce low birthweight rates and for the monitoring of the health of communities. Ward data on low birthweight can be used for correlation studies to show the many associations of social, economic and health factors with low birthweight and with each other. A recent government report shows a substantial increase in the prevalence of disability since 1985 which is partly a consequence of an increase in low birthweight and of a deterioration in the nutritional status of an important minority of poor families who are concentrated in inner city wards.

THE NEED FOR LOCAL HEALTH INDICATORS

The green paper Our Healthier Nation 1998 referred to "areas that are hardest hit by poor health" as "a key priority." The white paper Saving Lives: Our Healthier Nation 1999 said that to enable resources to be concentrated on the right areas and the right problems and to monitor progress more and better information at local level is needed.

A previous paper in this journal discussed the high cost to the individual and to society of low birthweight'. In a book entitled Low Birthweight published in the USA in 1995 a professor of epidemiology lists the increased risks as birthweight falls as deafness, blindness, epilepsy, chronic lung disease, learning disability and cerebral palsy2. It was emphasized that low birthweight babies do not necessarily suffer from any disability and that low birthweight is essentially a risk indicator. Risk of disability, particularly disabilities affecting the brain, increases as birthweight falls below optimum levels. Recent British research has reported that premature death in middle age from coronary heart disease increased as birthweights fell below 3,400g3 American research showed that learning ability increased on average up to and beyond birthweights of 3,4OOg4. The present paper discusses the geographical distribution of low birthweight which has a prevalence varying over a wide range, imposing very high costs on particular areas of our cities. Preventive services give the best pay-off 'If focussed on these areas.

The electoral ward is the best unit at which to record and measure information on the health of communities. Wards generally have a population of between 10,000 and 20,000 which is about the smallest population useful for many indicators. Low birthweight incidence is an unambiguous, unequivocal indicator not only of the health of babies but of women in their childbearing years. Birthweight is virtually always recorded and is believed to be reasonably accurate and in this respect is superior to many morbidity indicators which rely on sufferers reporting their illness. Health Authorities usually give low birthweight percentages by wards in their annual reports.

TABLE 1

Percentage of low birthweight in the wards of four cities and one London borough: highest and lowest quintiles

Table 1shows the low birthweight percentages by electoral wards of four English cities and one London borough ranked to show highest and lowest ward quintiles, a technique of presentation used in some Health Authority reports5,6,7,8,9. Low birthweight percentage is seen to vary from 3.0 per cent in Otley & Wharfedale in Leeds to 12.8 in Moss Side ward of Manchester. The wards included in the quintiles depend, of course, on the drawing of city boundaries which may or may not include areas of deprived or prosperous populations. In other parts of the United Kingdom wards have both higher and lower percentages of low birthweight babies than are seen in Table 1. Thus the South Wales Health Authority reports that Bro Taf which includes Cardiff has 4 out of the II 4 wards with only 2 per cent of low birthweight but three wards with 18, 19 and 20 percent in 1990 to 1994". Some Health Authorities do not publish low birthweight by wards. These are cases where, in the words of the white paper It is necessary "to strengthen availability of information about health at local level."

THE RISING INCIDENCE OF LOW BIRTHWEIGHT

During the years 1993 to 1997 the total number of births in the United Kingdom has been declining while the number of babies born less than 2,500g and less than 3,000g has been increasing as shown in Table 2". The number of babies born under 2,500g in the United Kingdom reached 55,785 in 1997, or 7.7% of all babies, but 177,097, or 24.4 per cent of all babies, were under 3,000g. At birthweights of 3,000g and above the risk of disability declines. More than a quarter of British babies are born too small. In some of the deprived wards of our cities the percentage of babies born under 3,000g is higher still, for example in Sheffield the highest figure is 32 percent, in Manchester 36 per cent, in Leeds 38 per cent and in the Handsworth and Aston wards of Birmingham 40 per cent of babies are at risk from being born under 3,000g.

TABLE 2

Percentages of babies born under 2,500g and under 3,000g to residents of the United Kingdom 1993-97

EUROPEAN COMPARISONS

Comparison of health indicators between countries are important because they show that it is possible to do better. There is nothing inevitable about the high and increasing percentage of babies born too small in the United Kingdom. The British Medical Association said in 199912:

"Figures for the World Health Organisation show that in 1992 the UK had the highest rate of low birthweight babies (less than 2,500g) in the EU."

The low birthweight percentages for 12 European countries of more recent dates are shown in Table 3 taken from the database of the World Health Organisation 13 . The most recent percentage is given for each country. The United Kingdom is seen to have the highest rate among these 12 countries.

It would be expected that the ranking of countries by birthweight of their babies would be reflected in the ranking of the health of their women of childbearing age in these same countries. The World Health Organisation publishes the untimely death-rates of women aged 15 to 59 in its annual reports". The United Kingdom is seen in Table 4 to have the highest death-rate for this age group of women of 17 European countries except for Portugal.

TABLE 3

Low birthweight percentages for live births in some European countries

TABLE 4

Untimely death of women in the Member States of the World Health Organisation 1998

TABLE 5

Coffelation matrix of low birthweight and socioeconomic factors in the 29 wards of Sheffield

Source: reference 7

LOW BIRTHWEIGHT AND SOCIOECONOMIC INDICATORS

Electoral ward data for unemployment, dependence on income support, educational achievement, hospital admission rates and many other variables are published by Health Authorities and local authorities and may be used for correlation studies. In some cities data are available at ward level for over 60 different variables. A correlation matrix using data for the 29 wards of Sheffield is shown in Table 5.

The first column in Table 5 gives correlation coefficients of low birthweight with seven variables, and the remaining 21 coefficients show the correlation of the other variables with each other. The Townsend Deprivation Index is seen to have the highest correlation with most variables which are all concerned in different ways with deprivation or low income. The high correlation of low birthweight with the Townsend Deprivation Index is seen in the last line of Table 5. The remaining lines describe some causes and consequences of low income. Low birthweight is seen to be commoner in wards with a high percentage of households with no earner or with high unemployment. Low birthweight is commoner in wards with a high percentage of households dependent on income support or other benefits. Low birthweight and poverty are also seen in Table 5 to be associated with educational failure shown by the percentage of children in these wards leaving school with no GCSEs or with less than 5+ GCSEs at A to C grades. Low birthweight is seen to be a social as well as a health indicator. It Is poor health and poor nutrition of mothers that is the main cause of low birthweight. What evidence is there then of inferior health and nutrition of men and women in the poorer wards of our cities?

TABLE 6

Limiting long term Illness among adults in wards of Birmingham with highest and lowest rates of low birthweight and deprivation scores 1991

Source: Census data, private households only. See reference 8

POOR HEALTH AT ALL AGES IS FOUND IN WARDS WITH HIGH RATES OF LOW BIRTHWEIGHT

The amount of limiting long term illness is one health statistic that is highly correlated with low birthweight as shown in Table 6 which shows the wards of Birmingham with the highest and lowest percentages of low birthweight. Three wards are seen to have approximately double the low birthweight percentages of the three most prosperous wards. These three deprived wards with the highest low birthweight are seen to have approximately twice as much limiting long term illness in the age groups 16 to 44 and 45 to 64 as the three most prosperous wards. Low birthweight is a good indicator of the risk of limiting long term illness of children and adults.

The Acheson report entitled Independent Inquiry into Inequalities in Health showed a standardised mortality ratio (SMR) per 100,000 for coronary heart disease under age 64 of 81 for Social Class I (professionals) and 235 for Social Class V (unskilled)15. However, the wards of cities show even larger inequalities. For example, between 1989 and 1991 SMRs for coronary heart disease in Leeds varied for men aged 25 to 64 from 178 in Burmantofts to 62 in Wetherby and for women varied from 237 to 35 in the same wards. In Sheffield the SMR for men and women varied from 40 in a prosperous ward to 221 in a poor ward. Coronary heart disease and low birthweight are correlated with the same socioeconomic indicators. Mortality from stroke under age 65 shows an even more striking association with low income and poverty than does coronary heart diseasel5. Disease of the vascular system in particular increases the hospital admission rates, placing an ever-'Increasing burden on health services as income declines.

WHICH NUTRIENT INTAKES DECLINE AS INCOME DECLINES?

All developed countries have dietary standards called in the USA Recommended Dietary Allowances or in the United Kingdom Reference Nutrient Intakes or in France Apports Nutritionnelles Conseillis 16. It is the basis of these allowances that if the intake of any nutrient is below the allowance there is an increased risk of health being affected, and the further the intake falls the greater the risk and the larger the number of people affected. Nutrition surveys show that the household consumption of every nutrient falls as average household income falls. The National Food Survey 1998 lists 30 nutrients all of which decline as income of the head of the household falls from £640 to under £160 a week". The survey shows that on low incomes the average intake of iron, zinc, magnesium and potassium is below the respective RNIs as shown in Table 7. Average intakes are higher than median intakes so more than half the population in households with incomes below £160 a week had intakes below the RNIS. Applying the basic meaning of the RNIs it must be concluded that people in households with £160 or less per week are at risk of ill health compared with people in households with higher incomes.

This may be illustrated from the wards of cities. Dependence on benefits is seen in Table 8 for the wards of Sheffield to be highly correlated with low birthweight. Men and women in receipt of benefits are a category of poor people whose diets have been reported in the Dietary and Nutritional Survey of British Adultsll. Their median intake in 1990 is compared with both UK and US recommendations in Table 8 and the lower 2.5 percentile of nutrient intakes of the whole population is also shown. Approximately 47.5 per cent of women and men dependent on benefits have nutrient intakes in the range between the 2.5 percentile and the median. Indeed Table 8 shows that about half the men and women dependent on benefits have intakes of nutrients below the intake recommended in either the UK or USA and are at increased risk of ill health of varying degrees.

TABLE 7

Household income and intakes of essential nutrients: percentage of Reference Nutrient Intake of energy, minerals and vitamins at two income levels

TABLE 8

Median intake of minerals and vitamins by men and women in receipt of benefits UK 1990 compared to recommendations

*10 under age 25

Source: see references 16, 18

REDUCING THE PERCENTAGE OF LOW BIRTHWEIGHT BABIES: A PUBLIC HEALTH POLICY

The World Health Organisation has distinguished for many years between the killing and the crippling effects of disease or, as we would say today, between the effects of illness on mortality and on disability. The prevention of disability improves the quality of life. Low birthweight is one indicator of the risk of disability and is also an indicator of poverty and deprivation of parents. Low birthweight can be prevented by improving the health and nutrition of mothers.

In Britain there have been two government surveys of the prevalence of disability among adults. The Prevalence of Disability among Adults 1985-6 was published in 1988 and Disabili in Great Britain 1996-7 was published in 1999. These surveys reported that there had been an increase from 5.780 to 8.582 million in the number of disabled adults living in private households during these ten years l9,20. The 1991 Census also reported that there were 522,239 persons suffering from a long term illness who were living in communal establishments.

The General Household Survey (GHS) reported on the prevalence of "limiting longstanding illness" in the British population in 12 surveys between 1972 and 1996 and found an increase of 47 per cent during these years These surveys include children and elderly people. The highest prevalence of disability was among the elderly but the younger the age group the higher was the percentage increase in disability.

The two surveys of disability among adults and the GHS are not strictly comparable. The disability surveys required factual or yes or no answers to some 50 questions. The GHS asked individuals only two questions relating to disability: whether they had a longstanding illness, disability or infirmity and if so whether it limited their activities. Both the disability surveys and the GHS, however, reported an increase in the prevalence of disability among men and women. Both the surveys and GHS show time trends and the likelihood of these trends continuing and of increasing disability in the population must be a matter of great concern and points to the need for preventive policies.

A recent conference on the review of welfare foods for poor women and children concluded that an integrated public health strategy to improve the health of children and the childbearing population would need a "cross-departmental Matemal and Child Health Task Force to formulate and implement such a strategy"". One of the ways the progress and success of such a strategy could be monitored would be by using the percentage of babies born under 2,500g and under 3,000g as indicators. The proposed Task Force should use ward data for monitoring to ensure that resources were con-centrated on the most vulnerable populations. The Task Force will need to promote action at local level beginning with pilot studies in the appropriate wards of cities relying on the initiative and support of local organisations.

The proposed Task Force would need to recommend expenditure of money and would be concerned with costs and benefits. The long term benefits of preventing low birthweight are large. Multicentre trials in the USA have shown, for example, that about 25 per cent of low birthweight babies have Intelligence Quotients below 65, a conventional threshold of what is described in the USA as mental subnormality but would today be described in the UK as serious learning disability 23. Such babies eventually need special educational help and may never be able to earn a living wage. The large pay-off from preventing learning disability is, however, some years into the future. For this reason some economic studies have emphasized the substantial pay-off in the short term in the first year of life of preventing low birthweight". Babies born under 2,500g spend between 1 and 100 days in intensive or special care units. The median stay in the UK is about 14 days and the cost about £8,000 as discussed in the previous paper'. This compares with the cost for the birth of a baby of higher birthweight of under £2,000. The cost every year to the health services of the UK of low birthweight babies in their first year of life is of the order of £400 million. There is also a substantial cost to parents and families. The prevention of low birthweight must be part of the action recommended by the Acheson report, Independent Inquiry into Ineq alities in Health 1998 which said:

"We recommend policies which improve the health and nutrition of women of childbearing age and their children."

REFERENCES

1. Wynn, M., Wynn, A. The problem of low birthweight, the cost and possibilities of prevention. Nutr Health, 1997; 11: 119-144.

2. Paneth, N.S. The problem of low birthweight. In: Low birth weight. Future of Children, 1995, 5: 1-231, 19-34.

3. Barker, D.J.P. Mothers, babies and disease in later life. BMJ Publishing Group, 1994.

4. Churchill, J.A., Neff, J.W., Caldwell, D.F. Birthweight and intelligence. Obstet Gynecol, 1966, 28: 435-9.

5. Manchester Health Authority. Public,health annual report 1997-98.

6. Lister, H., Simpkin, M., Jones, M. Redressing the balance: health and inequality in Leeds. Leeds Health for All, City Hall, Leeds, 1994.

7. Sheffield Joint Indicators Working Group. Sheffield Trends: annual compilation of indicators for Sheffield 1997. Statistical supplement 1997.

8. Birmingham Health Authority. Meeting the needs: Birmingham Public Health Report 1996-97. Birmingham public health information directory 1997.

9. Wynn, M., Wynn, A. Low birthweight in Haringey 1986 to 1993. Strategic Planning, Development and Equalities Unit, Haringey Borough Council.

10. Bro Taf Health Authority. The health of Bro Taf 1999 and personal communication.

11. Reply to Parliamentary question by Rt Hon Frank Field MP, 15th April 1999, column 333.

12. British Medical Association. Growing up in Britain: ensuring a health. future for our children. BMJ Publishing Group, 1999.

13. Low birthweight infant rates in the WHO European Region. WHO HFA database 24 August 1999.

14. World Health Organisation. Making a difference: the world health report 1999. Geneva: WHO.

15. Acheson, D. Independent Inqui into inequalities in health. London: Stationery Office 1998.

16. Wynn, M, Wynn, A. New nutritional recommendations are needed for childbearing. Nutr. Health 2000, 13: 199-21 1.

17. Ministry of Agriculture, Fisheries and Food. National food su e.@, 1998. London: Stationery Office, 1999.

18. Gregory, J, Foster, K, Tyler, H, Wiseman, M. The dieta and nutritional su e-v of British adults. London: HMSO, 1990.

19. Martin, J, Meltzer, H, Elliot, D. The prevalence of disability among adults. OPCS surveys of disability in Great Britain Report 1. London: HMSO. 1988.

20. Grundy, E., Ahlburg, D., Ali, M., Breeze, E., Sloggett, A. Disability in Great Britain. Research Report 94. London: Department of Social Security, 1999.

21. Thomas, M., Walker, A., Wilmot, A., Bennett, N. Living in Britain: results from the 1996 General Household Survey. ONS Social Survey Division. London: Stationery Office, 1998.

22. McLeish, 1. Report of the Welfare Foods Consultative Conference 7 December 1999. London:Maternity Alliance, 2000.

23. Gross, R.T., Brooks-Gunn, J., Spiker, D. Efficacy of early intervention for low birthweight premature infants and their families. The Infant Health and Development Program. In: Friedman, S.L., Sigman, S.D., eds. The ps 'vchological development of low birthweight children. Norwood, New Jersey: Ablex Publishing 1992.

24. Lewitt, E.M., Baker, L.S., Corman, H., Shiono, P.H. The direct cost of low birth weight, In: Low Birth Weight. Future of Childre 1995, 5: 35-56.

(Received 6 March, 2000)