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Chapter 7 - Fetal and child development

Catherine Peckham

Introduction

"Clinical futures" is an amalgam of speculations, guesses and estimates by people who have expertise in an aspect of the broad field of activity on which they are commenting. Because expert opinion is plentiful, virtually inexhaustible and rarely concordant, the seriousness and wisdom of such an exercise is questionable. However, people in general, and decision-makers in particular, actually do put weight on the uncertain opinions of experts. Informed conjecture is useful if it alerts us to opportunities, threats and choices that we might not otherwise have thought about.

So in this chapter we speculate on the potential impact of some of the new clinical technologies relevant to child health within the future social context of pregnancy and childhood. Social, political and economic forces operating not only within individual communities and countries but also at a global level will shape this future. These forces, and the response to them, will influence the provision of new technologies and will require a much greater degree of public involvement in defining and making choices.

A global perspective

Centuries separate the lives and fates of children living today in different parts of the globe. The contrasts are stark and are measurable at every level, affecting all aspects of life. Foreign debt cripples parts of Africa, Asia, and Latin America. It is estimated that if African countries did not have to pay foreign creditors, the money released would save the lives of more than 20 million children by the year 2000 and provide 90 million girls and women with access to basic education. The futures, clinical and otherwise, are bleak for children living in these countries, where basic human needs such as water, food, shelter and education are poorly provided or non-existent.

There are few grounds for optimism. Future technological developments will be geared towards the needs of industrialised and emerging economies, with poor countries losing out. There are many instances of benefits which are unequally distributed between poorer and richer countries. A current and specific example is the lack of access to antiretroviral therapy for children who are infected with the HIV virus in Africa, although these children represent 80% of those affected globally. Similarly, the emergence of what has been called "information capitalism" highlights the discrepancy between individuals who have and those who do not have the skills required for using information systems and the internet for commercial and other purposes. This will induce a widening gulf between societies that are able to exploit these technologies and those that are unable to do so. As a result, social and economic inequalities will be exacerbated and there will be an inevitable increase in crime, drug addiction, child labour, child prostitution, trade in children and commerce in human spare parts, which will have serious global as well as local consequences for health.

Ironically, as the developed world moves to protect the health of its population by introducing policies, for example to reduce smoking, the hungry global market seeks out new territories and threatens the health of individuals in developing countries. As smoking declines in Europe and North America, rates are increasing in developing countries at 3% per year. If current trends persist, it is estimated that 7 million people from developing countries will die every year from smoking-related diseases. Already lung cancer in China has been increasing at the rate of 4·5% per year. Cigarette smoking is an addiction that begins in childhood and adolescence and children are the vulnerable targets of the marketing campaigns promulgated by this multinational industry.

The clinical futures evoked in this chapter relate to technologies accessible to the developed world. We gaze into the global future through a distorting glass, the distortions imposed by economic inequality in priorities and provision.

The changing demographic structure of society

In many industrialised countries both fertility and family size have declined. In Europe the fertility rate is now below that required to replace the population. As a consequence the proportion of the whole population constituted by children is falling. In the UK children comprised 25% of the population in 1960 and 19·4% in 1996. The health and welfare of children has been peripheral to the concerns of the adult population with the focus in most developed countries being on the elderly. Thus, in the health and life sciences report from the UK Office of Science and Technology Foresight Exercise, children were not mentioned at all and ageing, degenerative disease and non-specific age-related cognitive decline were identified as priorities. This emphasis will need to change as society realises the importance of investing in children and their optimal development as a means of assuring stability, prosperity, competitiveness, and cultural vigour.

The drive for this shift of emphasis is clear as the next few decades will see a progressive reduction in the proportion of people in paid employment. In Britain in 1996 there were four people of working age for every pensioner, and by 2040 there will be two. As a consequence of these demographic changes, children will be valued more as the source from which society is replenished and continuously refreshed. The preparation for meeting the responsibility of supporting ageing families and for sustaining society economically will start in utero and continue through carefully designed approaches to early development and upbringing.

In the UK, marked changes in family structure will continue, reflecting single and serial parenting, smaller family size, changing gender roles and changing expectations, with deferral of pregnancy until the late thirties and early forties by some women and conception in the early teenage years by others. The number of children experiencing serial parents with an extended half sibling and stepsibling network will continue to grow as a consequence of divorce. There will be a challenge to provide support for lone and often isolated parents who lack an extended family and community structure. Similarly, planning for housing, education, transport, policing and green space will need to enhance opportunities for children to interact with each other.

Social, economic and environmental influences

In developed countries the gradient in child health that exists in relation to income and social status is becoming steeper. In the UK there has been both an absolute and relative lowering of economic well-being for children in low income households and stark recognition that the relative position of children and families in society is a powerful determinant of death and ill health. The influence of socioeconomic status on child health and development must not only be acknowledged but addressed efficiently. Political solutions outside the domain of health and related services will be sought but will be difficult to achieve without rigorous analysis of the issues and incisive problem solving. Health professionals will develop a powerful advocacy role for child health, a role that is currently weak and disjointed. Ways in which, for example, education, transport, food and fiscal policies influence child health positively or negatively will be clarified and used as yardsticks to judge the validity of proposed political solutions. Social interventions such as preschool education and parent support groups will be more firmly evidence based and their future evolution shaped by the prospective testing of models informed by social, biological and other relevant knowledge.

The impact on health of the physical environment - urban and rural - will dominate policies and criteria for planning, particularly for children and adolescents for whom injury is a leading cause of death and acquired disability. The influence of both the macro- and micro-environments will be tackled together and the nature and context of impacts at different stages in a child's development elucidated. This will form the basis for preventive strategies. For example, preventive interventions for childhood asthma will be based on an understanding of the relative contributions of the macro-environment (e.g., traffic fumes, air pollution) and the micro-environment (e.g., house dust mite, passive smoking, gas cooking, damp housing).

The impact of lifestyle and behaviour

Many adult lifestyles, relating for example to dietary patterns, physical activity and risk-taking behaviour, are laid down in childhood and adolescence. Because of the changes in social patterns within families, healthy lifestyles will be more difficult to maintain in the future. Passive entertainment such as television viewing and computer games, physical inactivity and meals as isolated rather than social events, will enhance risk factors for disease in adult life and result in a downward shift in the age at onset of conditions such as osteoporosis and cardiovascular disease. This trend will place demands on health services and offset the benefits that may have accrued from other lifestyle changes, such as a reduction in smoking. Rather than changing lifestyle, there will be an increasing medicalisation of high-risk groups designed to prevent the consequences of an unhealthy lifestyle. There will be increased reliance on pills rather than exercise for osteoporosis, on antidepressants instead of social support for depression, and on usage of cholesterol-lowering drugs in later life instead of dietary change. There will be a continued reduction in the age at first sexual intercourse, particularly for girls, with consequences for sexually transmitted disease, teenage pregnancy and risks of involuntary infertility in later life. Drug use, both legal and illegal, will rise leading to increasing addiction among the young.

Changing patterns of childhood morbidity

With the development of new vaccines and a reduction in infectious diseases, the major burden of childhood disease will be due to chronic conditions such as asthma, diabetes and disability, particularly that arising from the increasing survival of very premature infants. Cure rates from childhood cancer will continue to improve and children with conditions such as cystic fibrosis will have an extended lifespan. However, at the same time there will be a rise in problems reflecting lifestyle and other issues, including obesity, anorexia, and behavioural disorders. We are only just beginning to address the influence this may have for adults.

Novel and non-invasive routes of vaccine administration will be used, such as genetically modified food or aerosols, and new and effective combination vaccines will be available for a wider number of infections ranging from HIV to otitis media. Immunisation will continue to have a huge impact in reducing the mortality and morbidity associated with childhood infections and polio will have been eradicated globally. However, adults will require repeated vaccination into old age in order to maintain adequate levels of immunity throughout life. Paradoxically, despite the declining incidence of infectious disease, high vaccination levels will be difficult to maintain as belief in the need for "herd" immunity becomes dominated by individual concerns. A growing group of parents, with no personal experience of the infectious diseases vaccines aim to prevent, will not perceive the need to continue to have their child protected and the focus will be on the potential harm of immunisation. Onset of childhood conditions which are temporally associated with immunisation will fuel the deep rooted belief that immunisation causes all kinds of health problems and damages the immune system. New outbreaks of "old diseases" such as rubella will happen, as a result of declining immunity and increased travel to areas where these diseases are still prevalent, leading to, for example, the birth of infants with congenital rubella. At the same time, there will be ongoing debate as to when and to whom the new vaccines, for example against cancer, should be given. Antibiotic drug resistance, with fewer antibiotics available for treatment of childhood infections, will stimulate vaccine development.

The adult as a grown-up child: early determinants of future disease

Much of what is said in this chapter concentrates on features of fetal life and childhood, which are precursors of health and ill health in adults. Factors that influence health may operate independently at an early stage of development or in the young child, or interact with influences that continue throughout adolescence into adult life. An increasing and substantial number of adults will have received treatment for a childhood condition that was previously fatal. At present about 1 in 1000 adults in the UK are survivors of childhood cancer and this proportion will grow. Children surviving neonatal intensive care, better management of previously lethal inherited conditions such as cystic fibrosis, and successful treatment for congenital anomalies will add to this pool. In some cases this will have a direct impact on adult medicine and health-care resources, for example through longer survival from chronic disease. In other cases there may be undetected - possibly genetic - sequelae which will add in the short or longer term to adult burdens of ill health.

Longitudinal studies will elucidate the causal pathways that link early life, childhood development, and adult health status. For some conditions, such as diabetes and heart and lung disease, these pathways will be traced back to factors operating in fetal life including the intrauterine environment. The effects of continuity of exposure through life to factors that influence the intrauterine environment and that also influence childhood development and adult disease will be clarified. For example, low weight at birth, which is itself a marker of socioeconomic status, is associated with continuing socioeconomic disadvantage throughout childhood and adolescence. The complex biological and social mechanisms that result in low weight at birth will be understood and this will lead to the design of effective preventive interventions.

There will be firm evidence that juvenile delinquency and adult criminal activity can be predicted in early life and that its cause is largely due to poor parenting and deprived backgrounds. There will be accumulating evidence to show that interventions to mitigate or avoid the intergenerational consequences of poor parenting for vulnerable children are successful and highly cost effective.

Pregnancy and childbirth

The risk of pathology before or after birth is set, to an unknown extent, by the genetic constitution of the mother and the father and the genes inherited by the child. The expression of risk is modulated by environmental factors in utero and postnatally, through to adult life and old age. The genetic constitution of the mother and father interacting with external factors will shape the child's development postnatally into adolescence and beyond.

In general, scientists will continue to find it easier and more attractive to tackle genetic rather than environmental questions. However, there will be public and political pressure to identify effective secondary preventive interventions, thereby giving more priority to characterising gene-environment interactions. The influence of maternal genetic and non-genetic factors on the milieu of pregnancy, operating, for example, through placental function as well as through external influences such as food intake, alcohol and smoking, will be clarified.

As these influences are better understood there will be increased emphasis on pre-fertilisation parental fitness, with women offered screening for factors likely to affect the future fetus, such as genotype, infection, and nutrition. Uterus transplants will be available for women who require them. The prevention, postponement or attenuation of adult disease and the modulation of ageing processes will be sought through early interventions. This will lead to pressure for preconception and preimplantation screening. There may also be increased demand for gender selection. By cloning sections of DNA that code for physical or mental features, genetic engineering will have the potential to produce designer babies, but only for those that can afford it. As genetic risk is better understood there will be pressure for interventions where the DNA from somatic cells of genetically "clean" or "desirable" sources will be used to fertilise ova also from carefully selected sources. This will raise issues of discrimination, morality, ethics, and public acceptance.

Wider ranging genetic screening based on the recovery of fetal cells from maternal blood will be undertaken to determine fetal genotype. The majority of gene defects resulting in childhood disorders and other inherited conditions will be detectable, but identification of genes in the conceptus or fetus, such as the BRCA mutations, which may increase susceptibility to disease in adult life, through interaction with environmental factors, will lead to action without adequate knowledge.

This will have implications for primary prevention through preimplantation diagnosis as well as for secondary prevention through termination of pregnancy and in utero gene therapy. The feasibility of preventing fetal abnormalities and genetically inherited disorders will challenge society to retain a pluralistic approach where individual choice is respected and supported. Alternatively, parents who proceed with a pregnancy in the knowledge that their fetus is handicapped or at very high risk of a disorder, such as Down syndrome, cystic fibrosis or a severe congenital abnormality, may be stigmatised by society and expected to meet the costs of care and treatment. At the same time, failure to detect affected pregnancies through established screening programmes will raise the prospect of legal actions by children against their parents, the state, or those responsible for "intra-uterine health care".

The expectation will be that women should have healthy babies with everything done to minimise risk to the fetus and newborn, bearing in mind that most babies are born healthy with the minimum amount of medical intervention and that most women want reassurance that their baby is normal. User-friendly methods of monitoring fetal development will be devised for pregnant women to use at home. The images and information so generated will be relayed digitally by telephone to a central service where automated assessment using preset criteria will be used to alert professionals and the pregnant woman to the need for review. Such measures will lead to the compilation of a large body of longitudinal data contributing to a better understanding of intrauterine growth and development.

Women will continue to want to have their babies delivered by friendly, professionally capable staff in a non-threatening environment. Few women will seek home births as a positive option and it seems unlikely, at least in Britain, that there will be an increased demand for home deliveries over the coming decades. Instead, emphasis will be placed on providing a homely environment in hospital where the woman feels in control and has rapid access to expert obstetric or paediatric facilities if required.

Health and development in utero and in childhood: a new focus for medicine

Health and development in utero and in the early childhood years will emerge as the central focus of medicine, as the genesis of adult disease and ageing is understood and the possibilities of influencing physical, medical and social development are recognised and exploited. There will be a tension between the application of technology to achieve the perfect individual and its use to understand how environmental changes may be used to maximise the potential of individuals as they are.

There will be major advances in functional imaging techniques to detect structural abnormalities and in the assessment of fetal organ function. Imaging technology will substitute completely for invasive diagnosis. Three-dimensional ultrasonographic, echocardiographic and magnetic resonance imaging will become the gold standard for the next generation, not only to make accurate anatomical diagnosis but also to provide detailed functional assessments before, during and after therapeutic interventions. Very fast acquisition sequences for magnetic resonance imaging will be available and will be exploited to image the fetus. Most anatomical abnormalities of the fetus will be detected in the first half of pregnancy, even those that are relatively subtle and effectively treated, such as cleft palate or talipes.

Brain function will be assessed through qualitative assessment of neuronal migration, synaptogenesis, and cerebral biochemical function. Additional insights will be provided by magnetic resonance and/or near infrared spectroscopy with magnetic stimulation of developing neural pathways being used to assess the developing motor system of the early fetus. Non-invasive, probably transcutaneous methods, will be used to monitor the health of babies in utero through the mother's abdominal wall. Fetal well-being will also be assessed through measurement of acid balance, blood gases, cardiovascular function, and metabolic state.

A range of interventions will be developed, including technologically based ways of influencing fetal growth and development, for example through modifying placental function and modulating nutrition in utero. More effective methods to support the compromised fetus into the third trimester of pregnancy will be available to allow for safe delivery of the premature newborn infant.

Twins and multiple births expose the babies to a significantly increased risk of handicap. As there is no biological advantage to being a twin, improved methods will be developed for reducing the number of multiple pregnancies. Multiple births as a result of infertility treatment are already being discouraged, and it is probable that multiple birth as a result of any form of infertility treatment will become unacceptable. This will raise the issue of selective termination of a co-twin early in pregnancy for those multiple births occurring spontaneously. The ethics of this will be more widely discussed in view of the doubling of risk of disability to a twin pair.

Although early and accurate assessment of organ function will be possible in the first trimester it is unlikely that fetal surgery will prove effective at this stage. Termination of pregnancy will therefore remain the only therapeutic option. However, detection of abnormalities in the second trimester will open the way for fetal surgery. Fetal organ transplantation will become an effective and feasible form of therapy for all major systems, but this will not be necessary in the majority of cases until near, or at the time, of delivery. Rather than planning an intervention during pregnancy, early detection with delivery in the appropriate surgical/transplantation environment will be necessary. In the early 1980s, the introduction of intrauterine echocardiographic diagnosis of congenital heart disease led to the termination of fetuses with highly correctable congenital malformations, a trend that was reversed in the early 1990s. The decision to terminate or operate will be clearer, as more refined assessments of congenital heart disease in the fetus will be available together with information on the long term results of repaired congenital heart disease.

Ethical dilemmas relating to the concept of the "perfect fetus" will be revisited, with tensions between the rights of the fetus, the mother and society to determine the fate of affected pregnancies where the fetal abnormality is compatible with life, and treatable but not curable. The combination of improved fetal surveillance, enhanced expectations of a normal child and the ready acceptance of termination will make ethical decisions difficult, particularly for minor or treatable abnormalities or for those of uncertain outcome.

Prematurity

There are many reasons for premature birth which need to be considered separately in order to understand whether prevention is desirable or feasible. At present 7% of babies born in the UK are premature (<37 completed weeks of pregnancy) and 1% are severely premature (birthweight <1500 g or gestation <30 weeks). These proportions will not decline and may well increase, with a greater proportion born severely premature. This increase will be mainly due to iatrogenic premature delivery of women not in labour.

Where chronic or sporadic maternal conditions predispose women to recurrent premature delivery, the fetus is probably healthy and suppression of prematurity is appropriate. More effective treatment will be available to suppress premature labour. Maternal infections will continue to trigger early onset of labour. Although screening will be in place and there will be more effective antimicrobials, antibiotic resistance will become a major problem. However, vaccines against important pathogens such as streptococcus B will become increasingly available.

Babies who fail to thrive in utero will be delivered in a very premature state as technological advances will ensure that the premature delivery of a severely compromised fetus offers a higher chance of survival in the neonatal intensive care unit than in the uterus. However, this practice will have profound implications for the quality of life of survivors and their families. Some women will suffer multiple miscarriage or very early onset of premature labour despite treatment. For those women with an apparently healthy conceptus, an artificial womb will become a reality. Within 10 years it will be possible to transplant a viable immature fetus from the mother into an artificial environment which will nurture the pregnancy to a point where safe delivery can occur. Factors that will inhibit this from happening are ethical and financial. Although it will be difficult to reconcile the costs and benefits of this form of treatment, which will be appropriate for perhaps only 0·1% of fertile women, the pressure of potential beneficiaries supported by the media will be emotive and persuasive.

Consequences of premature birth

Currently approximately 10% of babies born very prematurely survive with some disability, of which 5% will be severely disabled. A further 20-30% of very immature babies who survive will have disabilities with no "hard" neurological signs. These disabilities include clumsiness, attention deficit disorder, poor school performance, and mild to moderate learning problems. These problems will not feature in the neonatal period, where questions of life, death and severe handicap are to the fore, but will emerge later when such "minor" disabilities will cause major problems in school and at home.

The full range of long-term psychological sequelae of extreme prematurity are only now beginning to be appreciated. Understanding of the mechanisms underlying the psychological development of very premature infants will have accumulated and this will be used to devise successful preventive strategies. There are 50-60 times more extremely low birth weight (<1000 g) children surviving now compared with the early 1960s. The impact of this on the community will be substantial, as the prevalence of psychological deficits will be substantially greater although levels of disability in this group will have declined.

The increased risk of severe disability in premature infants will be predicted by methods for assessing the developing brain. Both motor and cognitive function, and hearing and vision will be assessed in the first few days after birth. It will be possible to make an accurate prognosis of a very high risk of poor outcome due to acquired brain damage. If a critical amount of brain damage has been sustained, it is unlikely that this will prove treatable. Prognosis, based on these techniques, might inform withdrawal of life support and, in some instances, the case for active euthanasia will be strongly argued.

Acquired damage to the developing brain due to prematurity, birth injury, or asphyxia, will be treated to prevent, or ameliorate, functional brain damage. High-risk babies will be treated prior to premature delivery by medication administered to the mother. These medicines will have a range of actions designed to stabilise cerebral blood flow, reduce coagulation disturbances, and minimise free radical injury. Effective intervention therapies in babies with established brain injury will also be developed. Brain hypothermia is promising but safety issues need to be resolved. It may well be used for acute brain injury in older children and adults. However, it is unlikely that there will be one therapy that achieves neuroprotection through all the possible pathways, and a combination of pharmaceutical and technological interventions will be used.

A number of strategies will be developed to understand the causes of disabilities in premature infants and to reduce their incidence. The approaches will be either interventional or enhancement related. The causes of less severe neurological disability are many, but nutrition is likely to play an important role. Human-based milk formulas will be adapted to the needs of prematurely born infants and will be based on recombinant DNA technology so that the fat and protein will be human rather than cow or vegetable. More appropriate nutrition (both milk based and parenteral) will reduce neuronal dropout as a result of premature birth. Antioxidants, such as vitamin E, will be given to reduce cytokine-induced neuronal damage, either during pregnancy to women at high risk of premature delivery, or to the premature baby.

Enhancement therapy will be directed towards providing an appropriately enriched environment for children at risk of developmental problems. Special programmes will be designed to provide the requisite stimulation for encouraging the relatively "plastic" immature brain to compensate for damaged areas. These therapies, provided by a new cadre of generic teachers with advanced therapy skills, will also be valuable for children from deprived backgrounds who will benefit from focused stimulation. These programmes will start at, or shortly after, birth and continue for the first few years before dovetailing into mainline schooling.

Paediatric surgical issues: the example of congenital heart disease

It will make a nice bedtime story for my great-grandchildren to tell them that one of their ancestors spent his life tying knots inside the hearts of small babies

Basic surgical techniques such as the use of threads to approximate anatomic structures will be relegated to history books as sealing agents replace sewing procedures. With optical technology, it will be possible to see through blood and to repair some cardiovascular defects using endovascular devices without opening the heart or the great vessels. Video-assisted technology and telesurgery will make it possible to operate from a distance and greater precision and accuracy of surgical repairs will be achieved. Patients will have the choice between a machine-made or a handmade repair of their heart defect. Minimally invasive cardiac surgery, currently only used in adults, will be undertaken in children.

Experimentation with alternative methods of providing extra- corporeal circulation will feature, although cardiopulmonary bypass will remain necessary for some surgical procedures. The cascade of events leading to tissue and cellular injury following cardiopulmonary bypass will be understood and lead to novel approaches to prevent and/or treat the side effects of this procedure. Transgenic blood, blood substitutes and prepared blood that is safe will provide blood devoid of human risk factors. The risk of transmitting viruses from animal donors will remain a concern.

Cardiac substitutes

Although there will be complete tolerance of transplanted human organs, their use will be limited because of shortage of donors. Xenotransplantation and organ cloning will be used to provide alternative sources of organs. The development of transgenic animals will make xenotransplantation feasible, but the problem of possible viral contamination of the recipient and, more importantly, of the human species, will restrict their use. Cloning of spare parts, for example a spare heart from fetal cells, will enable transplants to be carried out at birth or even before, using the maternal placenta as a natural "heart lung machine". Pending the discovery of biocompatible and non-thrombogenic material and of implantable long-lasting power sources, artificial mechanical hearts may become an alternative.

Genetic and molecular therapies

Current research in molecular and genetic engineering will produce a wealth of potential therapeutic opportunities. Developments in gene therapy will include the rapid induction of cell hypertrophy, for example to prepare a low pressure ventricle to serve the systemic circulation; the induction of proteins that facilitate recovery from ischaemic injury following repair of complex cardiac defects; and the induction of new myocyte growth, for example around an extracardiac conduit, to support the Fontan circulation. Rational drug design with enhanced target specificity will lead to the development of drugs acting on specific cells, such as lymphatic myocytes. This will be a major advance in the treatment of conditions that have in common interstitial oedema and effusions, such as congestive heart failure or the failing Fontan circulation.

Health care for children

As a group, children will continue to make low demands on the acute health-care system with a small proportion of severely ill children requiring specialist and intensive "high tech" medicine. The last century's iatrogenic epidemics of tonsillectomy and grommet insertion will be replaced by the medicalisation of children with societal diseases such as obesity, anorexia, hyperactivity, and attention deficit disorders, as well as addictions to tobacco, alcohol and other drugs.

Paediatric care will be further dichotomised between community-based and highly specialised care. Most sick children will not be seen in hospital and appropriate care will be given at home or in clinics close by. Hospital care will be reserved for those critically ill children who cannot be looked after safely in these settings. As a result, children's hospitals will become fewer in number, each providing care for a population of about 5 million people. Hospital services will revolve around the intensive care unit dealing with acute life threatening illness and trauma, supported by an appropriate concentration of specialised medical, nursing and other skills. The care of critically ill children will be greatly enhanced by advances in the non-invasive monitoring of organ systems. The need for invasive procedures will be minimised or avoided and more effective methods will be available for supporting the heart and respiratory systems. Respiratory failure will remain the major reason for children requiring intensive care. The role and the status of nurses and other key non-medical staff in highly specialised areas of practice will be acknowledged and upgraded to reflect their knowledge, expertise and responsibilities. A single hierarchy will emerge, with nurses and doctors occupying positions commensurate with their expertise and responsibilities.

Thus, there will be a progressive shift towards child health primary care for disease prevention and the management of acute and chronic illness and disability. The creation of large primary care consortia will lead to community-based medical subspecialisation with the disappearance of the general medical practitioner. Nurses and other non-medical staff will take on a range of specialised roles within primary care, but will also assume the generalist mantle. Case management advice and the monitoring of treatment and follow-up will be aided by telemedicine linkages within primary care, between patients and primary care, between primary care centres and hospitals and between hospitals. International transfer of information will become routine to aid the diagnosis and treatment of complex and rare problems. This will become a major route through which the expertise and facilities of the richer countries can be shared with the developing world.

Economic criteria will dominate policy decisions about the future of expensive high technology health care. High technology medicine will be performed exclusively in units, with a critical mass of patients supported by a team of highly specialised experts who will also play a role in research and development, as well as the training and education of future experts. What constitutes critical mass in terms of number of patients, number and diversity of staff and facilities, will be based on comparative economic and outcomes data, taking geographical location, population density and requirement for specialised care into account. The increased cost of the NHS will be such that care will become increasingly divorced from diagnosis, treatment and high technology procedures. Parents will become increasingly disenchanted with the failure of technology to live up to its expectation. The use of complementary medicine will gain widespread public acceptance. The new challenge will be to ensure that complementary medicines are fully integrated with orthodox medicine to enhance quality of life, while respecting the principles of scientific evaluation.

Outcomes-related accountability will provide the basis for liability and there will be an exponential rise in legal actions against surgeons in general, and paediatric cardiac surgeons in particular. Appropriate mechanisms for providing compensation against non-negligent harm resulting from medical and/or surgical interventions will be in place in some regions. Failures in high technology medicine - a hallmark of complex sociotechnical systems - will be examined as failures of a system as well as of an individual.

However, the changed pattern of delivery of orthodox health care to children will not address the roots of childhood health problems and community solutions will be sought. Unless they take on a child advocacy role, child health professionals may find themselves increasingly isolated, with society demanding more in relation to its children. Individuals will be identified from within communities to take responsibility for community issues such as teenage pregnancy. Cooperative health groups will be set up. Health visitors will be reinstated and work to identify vulnerable children at a stage when early intervention will have the greatest benefit. The school health service will re-emerge with a strengthened remit to support and promote lifestyle and behavioural practices compatible with longevity and reduced morbidity.

Future scenarios

New knowledge regarding the influence of psychosocial and socioeconomic factors and brain development will generate political controversy over the coming decades. Evidence of the importance of early childhood development as a lifelong determinant of health, well-being, and competence will threaten contemporary notions of family privacy and autonomy. This in turn will induce a protective reaction in favour of the exclusive right of the family to bring up children as it sees fit. At the same time, there will be a heightened sense of urgency to take collective responsibility for the early childhood years. The political left will focus on the equitable distribution of opportunities and the right will give emphasis to producing a cognitively sophisticated population which can "compete" in the global economy. These latent conflicts and tensions evoke a number of possible future scenarios. Two are presented: one we would like to see and the other we are afraid we will see.

The preferred scenario

Fifty years from now, there will be broad acceptance of the fundamental importance of nature-nurture interactions and arguments of a "nature versus nurture" debate will seem as crude and as sinister to us then as turn-of-the-century eugenics concepts do to us today. The scientific basis of this scenario will be a thorough understanding of the role of critical and sensitive periods in human brain development during the first 5 years of life. The crucial elements will be scientific consensus on "how critical is critical" and "how sensitive is sensitive?" In other words, to what extent windows of opportunity for the development of specific competencies in the brain "open" only once, and for circumscribed periods of time, and to what extent they can be stretched, re-opened, or efficiently replaced by alternative pathways which open in later life. This knowledge will be complemented by scientific development in two other areas.

First, outstanding issues surrounding the presence or absence of hierarchies in the development of brain competencies will be settled. Most important of these will be an understanding of the extent to which high quality emotional/affiliative experiences in the first 2 years of life are a precondition for successful intellectual development thereafter. Second, the extent to which specific early experiences, operating through mechanisms that act independently or together, affect subsequent health and well-being will be understood. These mechanisms may operate through exerting an effect irrespective of intervening experience (through latency); through life pathways that are engendered by early experiences (thus shaping their environment for opportunity); and through accumulation of risk or resilience according to the intensity and duration of developmentally significant experiences.

Each effect model will be shown to make important contributions, and the hidden political arguments which currently lead investigators and policy makers to advocate only one model at the expense of others will be pre-empted by coordinated analyses of birth cohort studies, producing a consensus on the relative importance of each model. Moreover, the axes which link the developing brain to the body's host defence mechanisms will be thoroughly characterised. We will understand how, when, and to what extent the psychoneuro-endocrine and psychoneuro-immune axes of the developing human become conditioned by psychosocial and socioeconomic experiences, and the degree to which systematic differences in the disposition of these axes, according to differential life experiences, contribute to socioeconomic gradients in health status.

The scientific understanding described above will be complemented by a renewed social commitment to children. The basic principle will be summarised by the maxim "do not let any group of children be left behind". The social corollary will be a policy of universal access to the conditions of healthy child development. Seven conditions will be identified: adequate income; access to facilities, emotional and social support; intellectual stimulation; adequate nutrition; sensible/quality care arrangements; individual advocacy/mentorship by at least one socially legitimate adult; and safety (ranging from vaccination to protect from infectious diseases to protection from physical abuse and unintentional injury).

Identifying this simple set of determinants of healthy child development will be the easy part, guaranteeing each child access to them will prove much harder. Within a few decades many countries will be using population-based, person-specific, longitudinal reporting systems to monitor progress and to evaluate periodically each child's access to the seven factors. The methods used to improve access will largely be left up to communities and families in order to minimise invasion of privacy, but a system of accountability for outcomes will be established, with greater or lesser enforceability, in different jurisdictions. Decisions will be made about how to use the threat of trade restrictions under international agreement, to bring wayward countries into line.

This focus on outcome will create pressure for progress in five domains. First, through developmental, psychological and brain imaging techniques, advances will be made in understanding individual variation in the development of specific competencies. In particular, we will know a great deal more about how to open developmental pathways through, for example, exposure to music, physical activity, the use of computer methods for combating dyslexia, and the balance between phonetics and whole language approaches to reading. The one-size-fits-all approach to education will be abandoned, although doing so without compromising universal access will prove to be difficult.

A second area of progress will help solve this latter problem. The inexorable decline in demand for acute care paediatric services, due to decreasing fertility rates and lower levels of paediatric morbidity, will lead to a planned re-deployment of child health care funding towards "child developmental resource centres". These centres will carry out individual developmental assessments, using state of the art techniques, in order to help parents and schools identify an individualised educational plan for each child and to help troubleshoot and modify the plan over time. By strategically merging paediatric and educational resources in this way, the process of developing special educational plans in the context of a universal education system will be made simpler.

The other three areas of progress will complement the above, but will take effect at a broader level of social aggregation. Neighbourhood environments will be required to provide a wide range of opportunities for physical stimulation and interaction with other children, through a variety of play spaces, especially where housing is physically restrictive to young children. A "life credit" system will be available for those leaving the workplace to take on primary childcare responsibilities; and a range of social policies to smooth out work-life/home-life conflicts will be implemented. Finally, pay scales for those providing licensed child care will rise dramatically to reflect the importance of this role, and infrastructure funding for child-care centres will be improved to reflect the developmental needs of young children.

The alternative scenario

The alternative scenario, which sadly we are more likely to see, will result from the following tendencies, which if they are not held in check will undermine the efforts outlined above. The potential exists for the development of genetic screening for multifactorial conditions, whose genetic contribution, if it exists at all, exists only in interaction with environmental factors. The conjunction of genetic screening, entrepreneurial initiative, and a willingness to rush to label individuals and fetuses as being "at risk" might well undermine efforts to improve the environment for child development. This will occur directly, through spending choices, and indirectly, through the promulgation of the notion of strict genetic determinism.

Although neurobiology has the potential to sharpen our understanding of how to create optimal environments for child development, this will not be regarded as a profitable area for investment. The lion's share of resources will go primarily to drug-related research, and 50 years from now the principles of child development will be no better understood than they are today. Polarisation between those who believe the environment is the most important determinant of health and those who believe that genetic risk is more important will increase. It is likely that social inequalities relating to lifestyles and prevention will get bigger despite increasing equity of access to health services.

More likely, and more insidious, would be a scenario in which those who understand the importance of early child development use their privileged knowledge to abandon those children who are at risk of failure, so that universal access to quality education would be progressively eroded through "reforms" in education funding mechanisms. Increased knowledge of the role of early child development may also bring back a form of aggressive "nanny-ism". This would mean an increasingly punitive attitude towards those who do not provide an exemplary environment for their children, but without distinguishing between those who lack resources and those who lack commitment. In an era where adoptable children will become increasingly scarce, child confiscations might become the preferred method of enhancing living conditions for children, rather than efforts at the cross-the-board improvements described above.

Conclusions

The goals of paediatric medicine are twofold: to foster the normal health and development of the child, and to advance the prevention and treatment of childhood illness. In pursuit of these goals, it is essential to consider the social and economic nature of the society in which children live, as well as the structure, circumstances and social and economic position of their own family within that society. A child's upbringing reflects this macroenvironment, with early experiences being further modified by the parenting they receive. For children's health particularly, there is a tension between socioeconomic and cultural factors on the one hand, and scientific and technological change on the other. The growing prominence of biotechnology emphasises the divorce of the individual from the social context. As Foucault observes, medicine conceives of diseases as "abstract essences", so that to perform a "medical reading" the doctor has "to take the patient into account only to place him in parentheses". This resonates with the sentiments expressed by Margaret Lock, the anthropologist, who described the scientific view of the body as "reified, isolated, decontextualised, and abstracted from real time, actual location and social space". This view, reinforced by commercial pressures and supported by professional and scientific interests, may be strategically useful for certain aspects of medicine. However, it will be increasingly challenged, as the interdependence between biology and social environment, which is particularly expressed by a mother and her developing child, becomes better understood. Sensitivity to, and respect for, this interdependence must provide a foundation for enlightened policies and practice.

The following contributed substantial passages which are incoporated in this chapter:

Carol Dezateux
Senior Lecturer, Epidemiology and Public Health, Institute of Child Health, London, UK

Clyde Hertzman
Associate Professor of Health Care and Epidemiology, Department of Health Care and Epidemiology, University of British Columbia, Vancouver, Canada

Marc de Leval
Lead Clinician in Cardiac Surgery, Great Ormond Street Hospital, London, UK

Malcolm Levene
Professor of Paediatrics, Division of Paedistrics and Child Health, The General Infirmary at Leeds, Leeds, UK

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