THE PROBLEM OF LOW BIRTHWEIGHT, THE COST AND POSSIBILITIES OF PREVENTION
ABSTRACT
Low birthweight is costly to sufferers and to society. Primary prevention gives benefits exceeding costs, but many plans to
prevent low birthweight, for example improvement in antenatal care, have failed because the intervention is too late.
Preconception care is generally necessary.
Poor maternal nutrition and infection are
the major causes of low birthweight.
WHY IS LOW BIRTHWEIGHT COSTLY?
Low birthweight is a problem for all countries. The US Institute of Medicine in 1985 published a volume entitled Preventing Low Birthweight, which began a summary by emphasizing the "large economic burden on our nation" caused by infants weighing less than 2,500g at birth because of the disability among surviving infants.1 Scandinavian studies during the first half of the century reported a four times overrepresentation of former low birthweight babies in institutions for the mentally subnormal, lame and blind and among recipients of pensions for some form of physical or mental disability.2
Low birthweight babies do not necessarily suffer from any disability but the risk of many kinds of disorder increases as birthweight falls below about 3,500g (7.7 lbs). The risk of cerebral palsy for different birthweights is shown using data from the Irish Republic in Figure 1.3 The risk is seen to be lowest in the birthweight range 3,500g to 4,500g. About half the birthweights in this particular study were within this optimum range. Seen only in the context of the prevention of cerebral palsy it may be concluded that in this Irish population all birthweights below 3,500 g are too low, because 73 per cent of all cerebral palsy is suffered by the 50 per cent of babies below the median birthweight of 3,500g of this population.
3,500g to 4,500g is not only the birthweight range with the lowest risk of cerebral palsy, but it is the optimum birthweight range in many other contexts. This is, for example, the range for lowest infant mortality in the official statistics of developed countries including France, Germany, Norway, Sweden and the U.S.A., and probably also for England and Wales. Mortality by infant birthweight for England and Wales in 1994 is shown in Figure 2, which shows the lowest mortality for birthweight over 3,500g, but the optimum range of 3,500 g to 4,500g is not shown in British statistics.4 The optimum birthweight range in less developed or underdeveloped countries and of immigrants from these countries is lower, but infant mortality begins to rise as birthweight falls below 3,000g in nearly all populations.5
The classic papers of John Churchill and colleagues from Wayne State University, Detroit, in the 1960s were among the first to show the correlation between birthweight and intelligence. The population of children studied were from middle-class families and were white. Controls were matched for mean social class score. These studies showed an increased risk of low IQ at birthweights below 2,500g, but showed much more than this:6
"The mean birth weight of high-IQ males was 3,750g in contrast to 3,020g for low IQ males... Excluding all cases in which birth weight was less than 2,500g and/or gestational age was less than 38 weeks resulted in a mean difference still significant at the p = 0.001 level."
The risks of cerebral palsy and of lowered IQ are increased by what appears. to be growth retardation or failure at some stage in embryonic or fetal development associated with birthweight below genetic potential. This conclusion is reinforced by the association of low birthweight and congenital malformation shown in Figure 3 using the official statistics for England and Wales in 1990 for central nervous malformations.7 These malformations happen during embryonic development early in pregnancy, and it is seen that the greater the slow-down in development the higher the risk of malformation.
While cerebral palsy may have its origin at any stage of development from a severe insult, or from an accident at any time of life, much of it is of early origin. A study from the University of California 1990 showed that 41 per cent of cases of cerebral palsy at age 5 had a severe congenital anomaly and a further 32 per cent had nonsevere birth defects several involving the face or head, suggesting underlying problems of embryogenesis involving the central nervous system.8
The risk of congenital malformation of the ears and eyes is shown in Figure 4 as increasing as birthweight falls below 3,500g. again using official statistics for England and Wales in 1990.7 The increased risk of congenital malformations of the heart and circulatory system with declining birthweight is shown in Figure 5. These malformations notified during the first week of life are only a minority of the malformations discovered during the first two years of life, which were insufficiently severe for early diagnosis. Sixtyeight per cent of malformations are found in babies below optimum birthweight and over half in the range of 2,500g to 3,500 g where the risk is not so high as for the smallest babies but numbers are much larger.
Barker and colleagues of the British Medical Research Council traced a population of men born in one prosperous part of Hertfordshire whose birthweight had been measured by midwives and weights at one year had been recorded by health visitors during the years 1911 to 193O.8 Mean birthweight of 7,991 boys weighed at birth was 3,583g (7.9 lbs). Subsequent death rates from ischaemic heart disease were found to be correlated with birthweight and with weight at one year. It was concluded that boys who weighed below 3,400g (7.5 lbs) at birth were at particular risk and special promotion of postnatal growth may be important. These Hertfordshire studies also showed that low birthweight or low weight at one year of age increased the risk of impaired glucose tolerance and of type II diabetes in middle age.
Figures 1 to 5 all describe risks to the individual. Health professionals in clinical practice and their patients are concerned with personal, individual risks. Everyone concerned with public health and health services is also interested in the size of the problem and where the larger numbers are to be found. The administrative resources needed for personnel and hospitals and clinics depend upon numbers. The birthweight of 2,500g has shown itself for over a century to be a valuable indicator of the wellbeing of populations and women of reproductive age. However the figure of 2,500g is arbitrary. The Irish and West Australian surveys show about 30 per cent of cerebral palsy as associated with birthweight under 2,500g, but 75 per cent under 3,500g.3,10
The British Births 1970 Survey sponsored by the National Birthday Trust Fund found that:11
"The chances of survival declined sharply with decreasing birthweight, particularly for those babies below 3,000g."
3,000g was described as the "safe threshold" although the actual lowest mortality was in the range of 3,500g to 4,000g. The report of the survey expressed concern that between the 195812 and 1970 surveys there had been a "worrying increase in the proportion of babies who are born too small".
From the public health point of view 2,500g is not an acceptable threshold of normality. The majority of casualties after the first week of life, both deaths and cases of disability, are in the birthweight range of 2,500g to 3,500g. Size is only one factor associated with increased risk, but it is an important factor. A reduction in the number of casualties of many kinds would follow a reduction in the proportion of babies born weighing less than 3,500g (7.5 lbs).
WHERE IS LOW BIRTHWEIGHT TO BE FOUND?A valuable report on health inequalities within the city of Leeds provides an example of the range of low birthweight in one city.13 Leeds has a standard of living not far from the British average and is not untypical of provincial cities in health experience. Table 1 is based on a report entitled, Redressing the Balance, 1994; Health and Inequality in Leeds published by Leeds Health for All, which includes representatives of Leeds City Council and Leeds Health Authority. The percentage of babies weighing under 2,500g in 1991 is seen to range from 3.0 per cent in Otley and Wharfedale to 12.0 per cent in Burmantofts and over 10 per cent in 4 other wards. Of the 5 wards with more than 10 per cent of low birthweight babies only one, namely Chapel Allerton, has a high percentage of minority ethnic residents, 33.75 per cent. Burmantofts, and also Pudsey South and Hunslet, had only small minorities of 2 or 3 per cent.
TABLE 1
Babies in Leeds with weight under 2,500g born to mothers resident in 33 wards of the city; all live and still births during 1991
| babies born < 2500g | |
|---|---|
| ward | percentage |
| Burmantoffs | 12.0 |
| City and Holbeck | 10.8 |
| Chapel Allerton | 10.7 |
| Pudsey South | 10.2 |
| Hunslet | 10.1 |
| 10 wards | above average |
| 8 to 9.5 | |
| 3 wards | around city average of |
| 7.6 | |
| 10 wards | below average |
| 6.7 to 5.4 | |
| Pudsey North | 5.2 |
| Whinmoor | 4.6 |
| Garforth and Swillington | 4.5 |
| Moortown | 3.7 |
| Otley and Wharfedale | 3.0 |
Percentages of birthweights below 3,000g or 3,500g are not published for the Leeds wards but extrapolating, using the national ratios,4 gives estimates of 40 per cent below 3,000g in Burmantofts and 10 per cent in Otley and Wharfedale. The percentages for England and Wales in 1994 were 6.8 per cent below 2,500g, 22.9 per cent below 3,000g and 60.7 per cent below 3,500g.
The spread of 3 to 12 per cent in the percentage of low birthweight babies under 2,500g is not a consequence of better maternity or general health services in Otley and Wharfedale than in Burmantofts. The spread is not a result of any action by the NHS. Indeed the NHS spends more money per head in Burmantofts than in Otley and Wharfedale. In 1993 there were 67 per cent more Burmantofts residents receiving hospital care per thousand inhabitants than residents of Otley and Wharfedale, and of the two wards Burmantofts had a Standardised Morbidity Ratio 72 per cent higher and needed the larger number of hospital beds.
The more deprived areas of London share the experience of Burmantofts. Thus Homerton Hospital, Hackney, East London, recorded 12.1 per cent of low birthweight babies in 1994 and 10.8 per cent in 1995.14 London districts classified by the Department of the Environment as deprived have higher than average percentages of babies of low birthweight for example:925 Hackney Borough 9.3 per cent in 1995; Tower Hamlets 9.7 per cent in 1993; Newham 49.5 per cent in 1995. If the higher percentages of low birthweight in East London and in parts of our northern cities are not attributable to the NHS the explanation must be found in the environment of the mothers. Low birth-weight has been called, "the biological indicator of social deprivation".
WHAT HAS HISTORY TO TEACH US ABOUT LOW BIRTHWEIGHT?
Epidemics of low birthweight have been recorded in many countries and have been found to coincide with times of deprivation and hardship particularly food shortage. Figure 6 shows the epidemic in Leipzig following the second world war based on the records of the University Women's clinic.16 These years were described in the medical papers of the time as the "deprivation years" (die Notjahre) which followed the German defeat and interrupted food supplies. Such epidemics show that low birthweight is not only environmental in origin, but is caused by the environment around the time of childbearing.
It is seen in Figure 6 that before the world war the percentage of low birthweight babies in Leipzig, including stillbirths, was between 5 and 6 per cent. This compares with Leeds at 7.7 per cent and Manchester at 9 per cent in 1991. Indeed 24 out of 33 wards in Leeds had low birthweight percentages higher than Leipzig's 6 per cent. Low birthweight percentages in Leipzig only reached the 12 per cent of Burmantofts in 1947 during the worst of the postwar deprivation years in East Germany, when food shortage was at its worst.
While Leipzig in the 1930s had a low birthweight percentage comparing favourably with Britain today there are many communities with lower percentages of low birthweight than Leipzig Thus France had a low birthweight percentage below 2,500g of 5.2 per cent in 1981 including stillbirths. West Germany had a low birthweight percentage of 5.9 per cent of live births in 1975 or 6.3 per cent including still births. Spain has provinces with low birthweight percentages below 5 per cent and some below 4 per cent. Thus the city and province of Zaragoza with a population of 650,000, comparable with Leeds, had low birthweight percentages in the 1970s between 3 and 4 per cent.17 Sweden reported a low birthweight percentage of 4.2 per cent of live births as long ago as 1973.18 Norway has reported 3.2 per cent of live births with birthweights below 2,500g. Finland reported 4.1 per cent of low birthweight births for 1994 as shown in Table 2 by type of hospital. It is the practice in Finland to refer the more difficult cases to the university or central hospitals. There are, however, large areas of provincial Finland with low birthweight percentages below 2.
TABLE 2
Percentage of low birthweight babies (< 2,500g) born in FINLAND 1994 by place of birth
| place of birth | percentage of births | total number of births all weights |
|---|---|---|
| university hospitals | ||
| (yliopistosairaala) | 7.0 | 19,390 |
| other central hospitals | ||
| (keskussairaala) | 3.9 | 23,891 |
| regional hospitals | ||
| (aluesairaala) | 1.9 | 15,316 |
| large local hospitals | ||
| (iso paikallissairaala) | 2.6 | 5,691 |
| health centres | ||
| (terveyskeskua) | 1.1 | 702 |
| Total all Finland | ||
| (yhteensa) | 4.1 | 65,730 |
If Otley and Wharfedale and Zaragoza and Norway and parts of Finland can reduce low birthweight percentages to 3 and even 7 2 per cent, there is prima facie evidence for believing that low birthweight is preventable at least down to these lower percentages.
WHERE DOES THE COST OF LOW BIRTHWEIGHT FALL?
In developed countries society has attempted to compensate for low birthweight by the development of services particularly for neonatal care, which have been increasing worldwide. The resources involved are substantial. A 1992 paper in Pediatrics writes:19
"The cost of neonatal intensive care in Florida is enormous. Combined total costs from all hospital providers exceed $100 million a year."
A Californian symposium entitled Low birth weight, from the Center for the Future of Children and National Bureau of Economic Research, included estimates of the cost of neonatal care for the U.S.A. as a whole.20 Costs were shown to increase as birthweight falls averaging $6,200 per neonate in the 1,500g to 2,500g weight bracket rising to $26,000 per neonate weighing below 1,500g, both estimates being incremental costs over and above the average cost for the birth of a normal baby of $2,000.
Overall costs of neonatal care for the United Kingdom have not been found, but studies have been published for Leeds,21 SE Staffordshire,22 Birmingham,23 Mersey Region and Liverpool24 and for the Trent Regional Health Authority.25 Costs per day for intensive care appear to average about £500, but vary widely. Costs for special care, that is for babies not requiring mechanical ventilation or parenteral feeding, are much lower, perhaps less than half the cost of intensive care, but again vary widely. The cost of the individual baby depends upon length of the stay in intensive and special care which varies from 1 to 100 or more days, the median being around 14 days. The overall cost per million population may not be very different in Britain and the U.S.A. The Florida paper concludes:19
It once again points out the importance of prevention and the high cost of failure to use preventive approaches to neonatal intensive care as a means to reduce the overall costs." This informative paper was sponsored by the Florida Health Care Cost Containment Board and sought to justify greater effort on primary prevention solely because of the "enormous cost" of neonatal care. The Californian study concluded a long chapter entitled, The direct cost of low birth weight, with the advice:20
"Moreover, the payback from programs that are effective at reducing the prevalence of low birth weight should be quite rapid. The key action step is to identify such interventions and then provide the resources and leadership to see that they are effectively implemented."
Many babies are saved from potentially handicapping conditions by neonatal intensive care which is a highly skilled and developed branch of paediatrics. Death rates among the small babies, particularly the very small babies, have been reduced dramatically. However many survivors suffer from some degree of disability.26-27 This is another reason for asking "is primary prevention possible?" There is also a shortage of intensive care cots even in many developed countries, which is yet another reason for questions about primary prevention.
THE COST OF SPECIAL EDUCATION
Former low birthweight babies are overrepresented in special day schools for pupils with learning and behavioural difficulties. The accounts of one English education authority for 1995/6 show the average cost for special education as £11,268 per year per pupil for primary and secondary education. This compared with an average of £1,784 a year for primary and £2,398 for secondary school pupils for the same authority. Of the 369 average number of pupils receiving special education in the schools of this authority 301 or 82 per cent were suffering from some neurological disorder, that is some disorder involving the brain and nervous system.
Unfortunately all children who might benefit from special education do not receive it. We quote from a study of low birthweight children and their classroom controls from Nottingham:26
"No child in the control group scored an IQ below 74, whereas eight of the study children scored below 70. Such scores place them in the group in need of special education, but at the time of the study they were all in normal schools, without special help."
Neglect of such children greatly increases subsequent problems when they grow up.28
DISABILITY AND POVERTY
The main burden of the disorders of the central nervous system falls on the sufferers. Caring for a disabled child also requires more, sometimes much more parental time than the normal child, which reduces earning capacity. The career or employment of the mother is often prejudiced or interrupted. A disabled child frequently requires a higher expenditure for care and maintenance discussed in detail in the literature in particular in a book by Sally Baldwin entitled, The Costs of Caring 1985.29 Many subsequent publications, notably also from the Social Policy Research Unit at the University of York, 30 have discussed the problem of the care and maintenance of disabled persons of all ages.
In Britain serious cases of disability entitle sufferers or their carers to disability allowance or attendance allowance at the discretion of the Benefits Agency. In 1995 the higher rate Disability Living Allowance was £12.40 a week and the lower rate £12.40 a week.31The Disablement Income Group undertook an independent survey of the financial needs of the disabled and concluded that these modest allowances did not meet the real needs arising from disablement, and no awards were being made to many disabled persons.32 It was estimated in 1990 that there were 3,412,000 adults in severity categories 4 to 10 involving restriction of daily living activities.33
Less than half this number were receiving a Disability Living Allowance in 1994. Of the 1,450,600 awards of disability allowance in 1994 two-thirds were found in a sample survey by the Department of Social Security to have family income below £150 per week and 40 per cent to have family incomes below £100 per week. 31,34
Disability produces poverty. Poverty also produces disability. Where the percentage of low birthweights is high there will be more disabled children and adults because of the increased risk of disability associated with low birthweight shown in Figures 1 to 5. The wards of the city of Leeds like Burmantofts with high low birthweight percentages have poor populations with an exceptionally high percentage of rented accommodation and overcrowding. Burmantofts had 66 per cent of households living in rented accommodation compared with 22 per cent in Otley and Wharfedale. The 1991 Census found 16.97 per cent of unemployed in Burmantofts almost 4 times the unemployment percentage of 4.29 in Otley and Wharfedale.13 The 1991 Census also found 602 households with lone parents or 7.3 per cent, compared with 190 households in Otley and Wharfedale with lone parents or only 2.0 per cent. In 1991 the Jarman Underprivileged Area Score gave plus 35.09 for Burmantofts and minus 10.22 for Otley and Wharfedale. Low birthweight is highly correlated with the Jarman Score and also with the Townsend Material Deprivation Index.
Society has changed in many ways which makes social adaptation of the individual increasingly difficult. In particular there has been a great reduction in developed countries in the numbers employed in unskilled occupations. Job security increasingly depends on ever higher levels of training and education. Major occupations, for example driving a car, are only possible for persons who pass a driving test and whose eyesight is not too badly impaired. Ability to use a computer is necessary in more and more occupations. The premium on the ntegrity of the nervous system has been growing and seems likely to continue to grow. Opportunities for sufferers from leaming disabilities are declining.
THE GREAT AMERICAN CAMPAIGN TO REDUCE LOW BIRTHWEIGHT
On 3rd October 1977 the Comptroller General of the United States sent a report to the President of the Senate and the Speaker of the House of Representatives, that is to the Congress.35 The title of the report was:"Preventing mental retardation-more can be done." The second heading in the report was: "Prematurity and low birth weight.".
The Comptroller General submitted his report pursuant to his statutory responsibility for auditing and accounting and commenting on the activities of Departments, in this case the Department of Health, Education and Welfare (HEW). Mental retardation was costing the nation £ billions annually. In October 1977 the 99 page report had already been to the President's Committee on Mental Retardation who agreed the recommendations and said:35
"We cannot emphasize too much that prevention of mental retardation is both cost beneficial and cost effective and would underscore the report's emphasis in this area."
The President's Committee also explained that they would be meeting representatives of all Departments of Federal Government to help them initiate and expand those programs that would enable them to reduce the incidence of mental retardation. The whole interest in low birthweight at this level of Federal Government at this time was a result of reports that:35
"Mental retardation occurs much more frequently in premature or low birthweight infants than among full-term or normal birthweight infants."
The promotion of programs for the prevention of mental retardation have had the support of republican and democratic Presidents and of both0 sides of Congress. President Kennedy appointed a committee in 1961 to prepare a national plan to combat mental retardation. The President's Committee on Mental Retardation was established in 1966 and President Nixon directed Federal agencies in 1971 to put their full support behind this Committee.
The political concern in the U.S.A. with "disorders and disabilities that involve the brain" has continued until the present day and Public Law 101-58, 101st Congress, 1989 exhorted the Nation to, "recognize prevention and treatment of such disorders and disabilities as a health priority", and designated the decade beginning 1st January 1990 as "the Decade of the Brain". The main reason stated in the Public Law for this priority is the estimate that treatment, rehabilitation and related costs of disorders and disabilities that affect the brain represents a total economic burden of $305 billion annually and that 50 million Americans are affected every year.
It was reported to the US Congress as long ago as 1962 that injury or abnormality of the nervous system surpassed all other causes of long-term disability in the U.S.A. It was further reported that of the individuals already suffering some degree of disability at age 18 the origin of the disability was before birth in 75 per cent of cases and during childhood in 25 per cent.36 These percentages related to more or less severe disability requiring social security support; later evidence showed a reversal of these figures for less severe disability of which 75 per cent could be attributed to an unfavourable childhood environment.
A report prepared for the Congress of the United States 199028 quoted the National Academy of Sciences' research on children and adolescents with mental, behavioural and developmental disorders which concluded that 12 per cent of the 63 million children of the U.S.A. suffer from one or more mental disorders.37 This conclusion about American children was among the important reasons which led the 101st Congress in 1989 to designate the 1990s as the Decade of the Brain.
The English report entitled The Health of the Nation, published in 1992 said that:
"There is a commitment in this White Paper to the pursuit of 'health' in its widest sense, both within Government and beyond."
this report did not, however, include any programme for the prevention of "disorders and disabilities that involve the brain which is a health priority in the U.S.A. This report only has an "Appendix C" entitled "Mental Illness" concerned with the treatment of some types of mental illness with particular emphasis on the prevention of suicide.
The reason why two governments have different policies are generally complicated and often obscure. There are, however, several reasons for the American concern with primary prevention. Perhaps the first reason is that the U.S.A. has created a society where success, even employment, depends upon ability and education. Extensive mechanization and computerization has progressively eliminated unskilled jobs. "Disabilities that involve the brain" reduce ability to survive unaided in a highly competitive society like that of the U.S.A.
There is a second reason for concern with primary prevention namely the evidence that the cost and incidence of disabilities that involve the brain are increasing. For example the incidence of cerebral palsy has been increasing in many countries during the last 30 years in the lower birthweight range as illustrated for the Mersey Region in Figure 7. In this context cerebral palsy is only an example of one class of nervous system disorder associated with low birthweight. Impaired learning capacity is also associated with low birthweight. The increase in incidence is partly a consequence of improved survival..
The American programmes for the prevention of disabilities that involve the brain are primarily concerned with improving the quality of life of sufferers. The English programmes in The Health of the Nation are primarily concerned with increasing the expectation of life and have little to say about programmes for improving the quality of life, not only having no preventive programmes for disabilities involving the brain, but also disregarding other major causes of disability such as musculo-skeletal disorders. During recent years in Britain there has been a slow increase in expectation of life but an increase in the numbers of the disabled reducing their quality of life. If primary prevention is inadequate an increase year by year in the number of disabled persons appears to be inevitable. The balance between programmes
HAVE LOW BIRTHWEIGHT PERCENTAGES BEEN REDUCED BY BETTER ANTENATAL CARE?
After 35 years in the pursuit of policies in the U.S.A. for reducing disabilities affecting the brain by reducing the prevalence of preterm birth and low birthweight can we be wise after the event? Have the programmes for reducing low birthweight succeeded?
The main remedy for low birthweight proposed by the Comptroller General of the United States in 1977 was summarised in his report and was repeated in many subsequent papers:35
"Comprehensive prenatal care can help prevent low birth weight and prematurity, thereby reducing the incidence of mental retardation. However, many women receive no prenatal care and many more do not obtain prenatal care until very late in pregnancy."
Prenatal care in the U.S.A. is generally called antenatal care in Britain.
The policy is now 35 years old and had three parts; first to extend the care to all 5 pregnant women, secondly to persuade women to seek antenatal care very early in pregnancy, and thirdly to extend and improve the content of antenatal care. Official statistics show that these aims have been largely achieved. Antenatal care reached 80.2 per cent of mothers during the first trimester and a further 15.0 per cent during the second trimester during 1994.40 The content of antenatal care has improved. Have the results been as hoped for?
Alas, low birthweight percentage did not decline. An American symposium entitled, Preterm Birth, published in 1993 writes (41, p. 35):
"Low birth weight rates are essentially unchanged since 1950."
TABLE 3
Live births of low birthweight (< 2,500g): USA 1984 & 1994
year all races white black percentages 1984 6.7 5.6 12.6 1994 7.3 6.1 13.2
Source:See reference 40
Table 3 based on official statistics shows that low birthweight and preterm birth percentages in the U.S.A. were rising from 1984 to 1994.40 The report says:
"Low birthweight rose among singleton births to white mothers of all educational levels, including college educated married mothers."
Another American symposium of 231 pages published in 1995 entitled, Low Birth Weight, says about antenatal care:20
"Controlled trials have, by and large, failed to show effectiveness in preventing preterm birth whether the intervention is social support, enhanced prenatal care, early recognition of labor or pharmacological interruption of labor."
It is also pointed out in this volume (p82):
"The use of obstetrical technology appears to have little impact on reducing the occurrence of low birth weight or preterm birth."
Because antenatal care has not achieved the hoped-for reduction in low birthweight percentages it does not follow that it has been without important results. Antenatal care identified mothers at risk who require special care. For 1 /3 example a delay in threatened preterm birth for only two or three days may enable the mother to reach a hospital with an intensive care unit and receive treatment for an infection. A short delay of preterm birth also allows treatment of the mother with glucocorticoids to induce fetal lung maturation, which may reduce the risk of respiratory distress of the newbom. Over the years antenatal care has made an important contribution to reducing neonatal and maternal mortality more particularly by early identification of pregnancies at risk.
In Britain the antenatal programme entitled, "Changing Childbirth" has resulted in many improvements from the mothers" point of view.42 It has extended the mothers' choices of location and procedures at the time of childbirth and has improved services for women belonging to ethnic minorities. It has not, however, reduced the percentage of low birth weight babies born. In England and Wales the low birthweight percentages for live births (< 2,500g) were 6.60 in 1953 and 6.80 in 1994. The high percentages of low birthweight babies in places such as Hackney or Burmantofts seem unaffected by the service called, "Changing Childbirth".
Birthweight is a hard indicator associated with infant mortality, health of the baby, risk of many forms of disability including those affecting the brain, subsequent adult health and expectation of life. The failure of antenatal care to improve birthweight distributions has led to world-wide discussion of the need for a new approach. A paper from Johns Hopkins Hospital School of Public Health in the 1993 symposium on Preterm Birth concluded (43 p. 213):
"The reduction of low birthweight and preterm birthrates, particularly among black and poor women in the United States, is probably the single greatest health challenge in this country. Its achievement will require a concerted and cooperative effort between scientists, clinicians, public health officials and policymakers. The rewards of these efforts will rival the greatest achievements of medicine and public health."
THE EARLY ORIGINS OF LOW BIRTHWEIGHT AND PRETERM BIRTH
Evidence has accumulated showing that the reason antenatal care does not present low birthweight is that it starts too late. The variations in birthweight usually have an earlier origin.
The growth of a new baby is genetically programmed, and low birthweight is generally a consequence of growth failure at some stage resulting in failure to reach genetic potential. The documented causes of growth slow-down fall conveniently under 3 headings: defective nutrition, infection and harmful substances.
These three families of causes can act already before conception to upset the genetic programming both in women and men. Reproduction is most susceptible to damage in women during the 2 or 3 days before ovulation, when the oocyte divides at mejosis I to produce the gamete ready for fertilization. A paper in 1992 from the United States Environmental Protection Agency says about toxic drugs: "The greatest risk to the oocyte occurs on the days just prior to ovulation." These are the days of the late follicular stage. Fertilization generally follows within 2 or 3 days of ovulation and the end of the follicular stage.
There is a second highly susceptible period around meiosis II in the female and fertilization, shown by research in the U.S.A. at the Oak Ridge National Laboratory.45 Following penetration of the ovum by a sperm the male and female gametes proceed to integrate which is a process of great complexity. One paper refers to the exposed geometry or loose packaging of the genome at this time as conferring a "unique vulnerability".
This period of high susceptibility before and around conception is not only susceptible to toxic drugs but to other substances harmful at this time including alcohol and tobacco smoke and many drugs that may be beneficial at other times. During this period reproduction is also susceptible to defective nutrition.
A study of 513 women in Hackney, London, early in pregnancy found that the mothers of the smaller babies had diets with many components that were highly correlated with birthweight as shown in Table 4,47 The correlation coefficients only reached statistical significance for the smaller babies below the median birthweight of 3,270g. It was a reasonable inference that the intakes of the mothers of the larger babies with birthweights over 3,270g had adequate intakes of these nutrients and that variations in birthweight over 3,270g had causes other than nutrition. The minerals in Table 4 are associated with protein and in practice protein intake can7not be varied without at the same time varying the intake of these mineral fellow travellers. In this particular study protein plus its fellow travellers emerged as the most important correlate of birthweight. A different population might show a different result with, for examp1e, B vitamin deficiency more important than low protein.
TABLE 4
Maternal daily intakes most highly correlated with birthweight below median < 3270g for 255 London mothers 1991
| r | p | |
| protein | 0.238 | < 0.001 |
| energy | 0.225 | < 0.001 |
| minerals | ||
|---|---|---|
| magnesium | 0.253 | < 0.001 |
| iron | 0.247 | < 0.001 |
| phosphorus | 0.243 | < 0.001 |
| zinc | 0.238 | < 0.001 |
| potassium | 0.208 | < 0.001 |
| calcium | 0.184 | < 0.001 |
| vitamins | ||
| thiamin | 0.200 | < 0.001 |
| niacin | 0.198 | < 0.001 |
| pantothenic acid | 0.186 | 0.002 |
| riboflavin | 0.183 | 0.002 |
| folic acid | 0.173 | 0.003 |
| pyridoxine | 0.168 | 0.004 |
The intake of some nutrients in Table 4 is highly correlated with social class and with income.48 Protein intake is generally social class and income correlated, but total energy intake including fat and 1carbohydrate intakes are similar in all social classes. In contrast intakes of some minerals and vitamins have steep social class intake gradients. In the Hackney study intakes of magnesium and zinc among the minerals were most prejudiced by poverty, and intakes of folic acid and thiamin among the B vitamins. These social class gradients in nutrient intakes may go some way to explain the social class gradient in the incidence of low birthweight.
There is a long list of infections that have been shown to increase the risk of low birthweight, Maternal daily intakes most highly correlated with birthweight below median < 3270g for 255 London mothers 1991 possible to ensure immunity before embarking on pregnancy. This is so, for example, for rubella and measles which can cause congenital damage very early in the embryonic period. It is possible to check immunity with a blood test as part of preconception care and inoculate if indicated. When a woman is infected it is important for the infection to be diagnosed and treated when possible before a conception is attempted or risked. Some infections, notably viral infections, can damage male and female germ cells and genetic programming already during the sensitive period before conception. Antibiotics essential for the treatment of some infections are damaging to sperm and ovum, and to embryo and fetus, and should be used when possible some weeks before a conception is attempted. The infections involved may be classified into temporary fevers, localised infections and sexually transmitted diseases (STDs). Influenza is an example of a temporary fever with a long history as a cause of reproductive casualty.49 Urinary tract infection is an example of a localised infection shown in many studies to be associated with an increased rise of low birthweight. Chlamydia is currently the commonest sexually transmitted disease in most populations and is a major cause of male and female infertility and of pelvic inflammatory disease in women, and of low birthweight and pneumonia and other illness of the newborn. Some of these infections are called "diseases of opportunity" because their serious consequences are generally encountered in men and women with a general immune status temporarily or chronically defective. Members of the herpes family are examples. Defective nutrition is a major cause of a poor immune status. Improved nutrition is the main remedy in the event of infection with some viruses such as cytomegalovirus, an important and damaging member of the herpes family for which there is currently no other remedy.
GROWING AWARENESS OF IMPORTANCE OF PRECONCEPTION CARE
The first general prepregnancy clinic in the United Kingdom started at Queen Charlotte's Hospital for women in January 1978 on the initiative of Professor Geoffrey Chamberlain.51 The patients were mostly referred to this clinic by general practitioners because they had problems. In the same year 1978 a charity for the promotion of preconception care was founded called Foresight which in the current year 1996 has about 1,200 patients.52 This charity is a private medicine initiative and about 60 per cent of patients have a previous history of reproductive problems including infertility, miscarriage, low birth-weight, stillbirth and malformations. Foresight is a success story but only for the comparatively small number of couples who were able and chose to pay for a service which is not part of the National Health Service.53 Foresight data for 1990-92 found that 89 per cent of 367 couples had children subsequently with a birthweight mean of 3,265g (2,368-4,145g), and without a single newborn having to spend time in a special care baby unit. 217 of these couples had a previous history of reproductive problems including 139 with histories of one to five miscarriages.54 Other couples had a history of low birthweight, stillbirths, malformations and infertility. The preconception care procedures currently recommended by Foresight were published in book-form in 1995.53
The Maternity Alliance since its foundation in 1980 has provided information for both men and women on preconception care as a first aim of its educational publicity.55 The Matemity Alliance gave evidence to the Health Committee of the House of Commons in 1991 stressing that preconception care should be available from a wide variety of sources.56
The Health Committee decided to take evidence on preconception care in 1991 under the heading, Maternity Services: Preconception. The Royal College of Obstetricians and Gynaecologists, the Royal College of General Practitioners and the Royal College of Midwives each presented evidence on the scope and importance of preconception care. The written evidence of the RCOG stressed that preconception care is already available but "it is haphazard and poorly organised" and recommended "introducing audit of preconception care."
The Health Committee reported in the autumn of 1991.57 The report made 23 recommendations: for research on preconception factors affecting pregnancy outcome including maternal nutrition; on preconception care as a key area of work for the Health Education Authority; on health education in schools; on preconception care by primary health care teams and by family planning clinics; on genetic counselling; for research into the primary causes of neuro-developmental disorders. The Government replied to the Report of the House of Commons Health Committee with a White Paper which promised consideration of the recommendations, but said:58
"To devise specific programmes for those planning pregnancy would divert efforts and resources from this 'whole population approach' without, in the Government's view, corresponding benefits."
This Department of Health's concentration on "whole population problems" leads to neglect of the problems of childbearing, including the problem of low birthweight, which are, of course, all problems of quite small minorities of the population at any one time, but have far-reaching and expensive consequences.
The Government's "strategy for health in England" spelt out in The Health of the Nation in 1992 includes no programme for preventing low birthweight or for preconception care and explains in half a sentence that "maternal and child health" is an "area with existing initiatives which are sufficiently well developed not to require a key area status". The disinterest in low birthweight, preconception care and maternity and child health in British Government papers does not only reflect the views of the Conservative Party. The Labour Party and the Liberal Democrats also have no published policies in this area.
The Government has recommended that women should take folic acid pills before and after conception following the results of Medical Research Council participation in an international study which showed that folic acid supplements reduced the risk of neural tube defects. The response of women to this advice has so far been very disappointing partly because the need for folic acid is a curiously isolated component of the general education required about preconception health.59
The American Government initiated a major study of prenatal care which reported in 1989 in a publication of the US Department of Health and Human Services entitled, Caring for our Future.60 A preface by the Chairman emphasized the report's recommendation that, "preconceptional screening" should be accepted "as a normal part of women's health care". The first page of the report says that, "more emphasis on preconception and early pregnancy is the intended message of this report". The summary of the report stresses the importance of the health of women and men before conception:
"To ensure the health of the woman and the developing fetus, preconception care should be an integral part of prenatal care. Many of the medical conditions, personal behaviors and environmental hazards associated with the negative outcomes of pregnancy can be identified and should be modified or treated prior to conception. Care begun before pregnancy has great potential to assure health and ameliorate disease conditions for women. Such care also avoids negative effects on the fetus of maternal treatment."
The report advises that every woman, and when possible her partner, contemplating pregnancy within one year, should consult a preconception care provider. The report also stresses that because many pregnancies are not planned, primary care health services should include preconception counselling, when appropriate, in their contacts with women and men of reproductive age. Preconception health promotion has apparently reached the largest number of women in the U.S.A. when offered as part of the service provided by family planning clinics to women generally not yet intending to have a baby. Local health department clinics in North Carolina, for example, have reported that 89 per cent of family planning patients welcomed preconceptional counselling aimed at the assessment of the risks to the mother of a future pregnancy and risks to a future child. This programme was described in a book by Professors Robert Cefalo and Merry K. Moos in 1988.61
SUPPORT FOR LOCAL INITIATIVES
The problem of Burmantofts13 with 12 per cent of low birthweight and of the wards of other cities with high percentages of low birthweight are not "whole population problems". Low birthweight percentage is an indicator of the degree of deprivation of a community, and, as seen in Burmantofts, is also an indicator of the health of men and women in the particular community. Low birthweight has multiple causes connected with poverty and there are therefore many ways in which intervention could lower the prevalence.
Little progress is likely to be made in reducing the prevalence of low birthweight in deprived populations without improving the nutrition of women. Poor nutrition underlies much of the poor health of these populations including the higher levels of infection resulting from depression of immune status. Experience in Britain and other countries suggests that intervention to improve women's health, and reduce the consequences of illhealth to reproduction, must aim at improving nutrition. Families on low incomes have to economize on food to meet other pressing needs. However improving the quality and accessibility of shops or providing new food supplies may not be the first step that is needed in some areas. Improvement in diet in some areas can only follow other changes. Experience has shown that safety and security may come first. Women with and without children may be afraid to go out. There may be nowhere where children may play safely.
A study in one part of Burmantofts showed that the creation of a community centre where people can meet was essential for real progress to be made. The Leeds City Council established a "Community Food Project" in City and Holbeck, a ward with 10.8 per cent of low birthweight babies (< 2,500g) in 1991 and second highest in Leeds after Burmantofts with 12.0 per cent. The report on City and Holbeck in 1991 recommended:66
"There should be provision for mothers with young children to meet and eat together to reinforce healthy eating patterns, similar to luncheon clubs for the elderly."
At the time of writing this recommendation had not been acted upon because of shortage of funds.
The Low Income Project Team of the Department of Health published a report on improving food availability in a follow-up report to Health of the Nation in March 1966 and, under the heading "The key players", says:67
"The LIPT recommends that specific budget allocations should be made by Government epartments, local authorities and NHS Trusts to support community food projects . . . For example, a health Trust which is encouraged to recognize that (a) young women on low income are unlikely to be able to buy the food they need when pregnant and, (b) that low birth weight is linked to poor maternal diet, may wish to target funds towards food projects which aim to improve diet in this population."
The National Food Alliance of over 70 organizations68 has recently developed the Food Poverty Network, which has begun to compile a data base of community food projects recording local problems, successes and failures, to be made available to projects newly starting up. But projects require funding and as in City and Holbeck may never take off because of shortage of funds. Projects may begin with enthusiasm but subsequently fail for lack of funds. Benefits from well-conceived projects would, however, exceed the costs. Low birthweight is just one very expensive consequence of poor nutrition and illhealth that can be prevented.
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