Bi Puranen

Table of Contents

Summary

Background

Gender

Pregnancy and work

The future in the mother's womb

Mothers, children and health

Are the major diseases predestined by life in the womb?

Intrauterine stress

Early development of the brain

Are human beings imprinted too?

Summary

Today, pregnancy has become our most common sexually transmitted disease. Over 80 percent of pregnant women in Sweden take sick leave at the end of their pregnancies, and the length of this leave is increasing.

In few areas have there been such sweeping (and in the long run significant) changes of attitudes as on the subject of pregnancy and childbirth. These changes have also affected parents' strategies for combining careers and childbearing - production and reproduction. The cultural differences are substantial, both between immigrant groups and between different generations of Swedes. There are also great differences between popular prejudice and scientific fact.

Bi Puranen is a project leader and researcher at the Institute for Future Studies. She is managing the project "Pregnancy and work - women's and men's opportunities for combining production and reproduction" on behalf of the Work Environment Fund and the National Institute of Public Health.

Background

Today, pregnancy has become our most common sexually transmitted disease. Over 80 per cent of pregnant women in Sweden take sick leave at the end of their pregnancies, and the length of this leave is increasing.

Almost 80 per cent of women in Sweden of active age have both a job and children. There are almost as many women as men in the Swedish workforce today.1 This is a unique pattern. In most countries women disappear from the labour market when they marry and have children; sometimes they turn up again twenty years later in "the informal economy", invisible reinforcements for the labour market.

But the situation is changing rapidly around the world. This applies in particular to the leading industrial countries, e.g. Japan and many European countries (with the exception of Sweden, Ireland and Iceland). Fertility rates are falling, women are hesitating. They face a difficult choice: children and husband or the independence of an individual career? The losers are the unborn children - and men. An increasing number of women are refusing to fulfil their traditional role. The tendency is clear. In 1980, women in the European Union gave birth to 1.8 children on average; the rate today is 1.5 children per woman. According to an EU report published in the autumn of 1993, this is the lowest figure that has ever been recorded.2 In Spain and Italy the birthrate is as low as 1.2 and in Greece 1.4 children per woman. Furthermore, an increasing number of women live and look after their children alone. 20 per cent of all children in the EU are born out of wedlock. Divorce is on the increase and fewer and fewer people are getting married. The continental European system seems to erode the family more than the Swedish one, despite our high divorce rates, since the fertility rate in Sweden is over 2.1 children per woman.

As a result, Sweden has attracted growing attention. Sweden, with the highest female rate of employment in the world, nevertheless has a relatively high birthrate. In this country having children and a husband does not necessarily mean having to give up your career. "If they can do it, why can't we?"

Is the Swedish trend desirable? Or are women wearing themselves out? Do Swedish women have the strength to set an example?

Do women's heavy workloads affect their health? Can Swedish women cope with both a professional career, housework, self-fulfilment and relationships? Is employment the main problem? And what is all this doing to their health? Where is the dividing-line between health and unhealth?

In the 1980s sick leave, industrial injuries and early retirement increased much faster among women than among men. The "sickness index", which is based on these factors, increased by almost 13 days per year among Swedish women (1978-1989), while the increase among men was a mere two days.3 According to the more rough and ready official statistics, men are becoming increasingly healthy while women's health is deteriorating.

In 1991 I wrote a research report entitled "Is Women's Ill-health Due to Their Double Workload?" The report analysed the negative health trend for women in the 1980s.4 It confirmed the overall picture. Women's health is at risk. But their double workload is not the reason. The period during which they give birth to and raise small children is the most healthy period in their lives. Obviously, parental leave and leave for taking care of sick children may conceal a certain ill-health among women. An indication that these factors are not very significant is the fact that the number of days mothers take leave of absence to look after sick children has not increased as a result of the reduction in sickness benefit.5

In the 1980s those who were ill and took sick leave were mostly elderly women and very young women. The childbearing generation takes out sick leave mainly in conjunction with pregnancy, and this tendency is rising very fast.

A year after my report a comprehensive report published by Statistics Sweden confirmed my findings.6 Two-thirds of working women in Sweden are employed in the public sector, i.e. in health care, child care, care of the elderly, education and all the other services provided by public authorities.7 Two-thirds of men work in the private sector.

An EU report (from the Expert Group on Regional Development Research) established that women's rate of employment depends entirely on the future of the public sector. The group warns that the cuts being made today may lead to widespread unemployment among women.8

Many traditional women's jobs, such as office work, are now undergoing substantial change. The EU report mentioned above comes to the conclusion that women face extensive unemployment in future "unless, in fierce competition with men, women make dramatic breakthroughs in labour market sectors other than their traditional ones".9

Another risk is that, at the same time as unemployment is rising among men of all ages, women are having to bear an increasingly heavy burden both as regards unpaid and paid work. The 1990 Long-Term Planning Commission states: "The time spent by men on leisure activities and unpaid work is in fact greater than that spent by women on gainful employment."10

Men have reduced their working hours by almost a quarter, which is equivalent to an average of eight hours per week or ten working weeks per year (1963-1988).11

Women's participation in the labour market has at the same time increased, regardless of the method of calculation, and today they represent almost half the workforce. Mothers of small children, in particular, now work longer hours. According to the Commission, women also take a relatively large share of the work of looking after the children and doing the housework. The risk is that working women's combined workload of housework and paid work is too heavy, while unemployed women feel too little pressure and are in too little demand. When the pressure on them is too high or too low hey feel bad and perform even worse. Women tend to fill out the beginning and the end of all the curves, instead of being somewhere in the middle where the good life is. This provides food for thought about the future organization of work, but also of child care and care of the sick and the elderly.

Gender

Man is often described as a social creature. Nevertheless, a remarkable number of people tend to ignore the implications of this fact. We often analyse ourselves in biological terms. But if we are social creatures by nature, this means that our instinct is to build societies and that we can only understand our lives if we consistently analyse all human behaviour in a social and cultural context.

As regards the differences between men and women, we cannot only consider the sexes in relation to biological parameters; the social text context must always be taken into account. In all known societies and cultures the population is divided into two categories, which we usually call men and women. The biological definition is generally obvious. It is more difficult to define what we mean by male and female behaviour. The anthropologists use many different definitions depending on the group or culture they are studying. The variations are amazing; what is regarded as male in one culture may be regarded as female in another.12 Being a woman in Sweden and in New Guinea means two rather different things, although we still have much in common. By using the term gender we can analyse the various dimensions of sex.

Gender includes a pattern of various factors, some social and cultural, others psychological and some purely physical. The combination can, at the individual level, look very different. It is impossible therefore to distinguish between biological and social sex. Both are a part of the same social creature. In Swedish, this is sometimes called the gender system..13 This definition also comprises power.

In this survey, the term gender is used with reference to three different aspects:

1. Genetic gender, which is based on the genotype and combinations of the two chromosomes X and Y (XX=female and XY=male).

2. Somatic gender, which is based on the phenotype, in particular physical appearance, depends on hormonal influence and decides the sex of the foetus.

3. Social gender, which is based on cultural categories, how men and women are regarded in society, how they look, think, feel, dress, behave and look upon the world they live in.14

These three dimensions are far from clearcut. At the somatic level hormonal influence may lead to a contradiction between the individual's perception of his/her sex and the sex indicated by the chromosomes. The foetus is vulnerable in the womb, and intrauterine stress may, like the action of chemical substances in the workplace, smoking and alcohol, affect the child's future, for example its cognitive ability.

Social gender is affected by both the social and cultural environment, and is highly flexible and sensitive to power. Yvonne Hirdman, our first professor of women's studies, sees two "logics" as the mainstays of the system. The first is the logic of segregation, for example the segregated labour market. The other logic means that what you do, say, are and personify represents the genuinely human norm.15

These differences have often been described in very dramatic and mistaken terms, as when Freud called women the dark continent or when August Strindberg in The Father exclaims: "If it is true that we are descended from the apes, it must at least have been from two different species. We're not alike, are we?"16 But the biological differences between the sexes do not involve total heterogeneity, but a reproductive differentiation which also makes men and women dependent on one another.

Recognizing gender differences should not make us blind to the common ground between men and women. Regardless of their sex people have a common nature and a common, albeit unknown, potential coded into their DNA. This does not mean that DNA determines our behaviour. Culture creates a number of different possibilities depending on our genetic material. As individuals, we "respond" to the signals of both heredity and the environment. The genetic undercurrents have not yet been sufficiently researched.

In "Anatomy of Love" the anthropologist Helen Fisher poetically describes differences between male and female as follows: "On average, each gender has an undercurrent, a melody, a theme".17 She claims that these gender differences are meaningful in evolutionary terms.Another anthropologist, Cecil G. Helman, talks of a binary structure, by which he means the gender structure as well as our perceptions of illness.

Pregnancy and work

By the time people have reached the age of 50 they have superfluous capacity for which there is insufficient demand. The reproductive phase is the complete opposite: a total lack of time. 24 hours are not enough to do everything that is required of one. The contradiction between biology and life is especially apparent in connection with childbirth.

The conventional division into healthy and sick fails to cover the special condition of pregnancy. At the same time as increasing numbers of women are in work, they also give birth to increasing numbers of children. Most women simply cannot cope during the dramatic last months of pregnancy. The purely physical problems escalate; one woman in four suffers from back problems during pregnancy. Tiredness, numbness, bleeding, loosening of the joints, low blood counts and sleep disturbances are problems that often occur.18 Only recently has attention been paid to the mental problems. The difficulty of meeting all sorts of demands at the same time, which is partly associated with hormonal changes, is another problem.19 The work environment also affects the foetus and thus the health of future generations.20

The conflict is particularly acute as a result of all the cuts in the health insurance system. Today, pregnant women who cannot go on working can either take sick leave in the normal way, they can receive a pregnancy allowance for the last two months of their pregnancy or they can take out part of their parent's allowance before giving birth rather than after. The higher the employment rate among women, the fewer women take out their parent's allowance before the birth of their child. Mothers put the child's interests before their own.

Pregnancy allowances are normally only granted to women with physically demanding jobs, while women with intellectually demanding jobs and a lot of travel and conferences etc. are not considered eligible. Most women today have service jobs. For them the only feasible alternative is to go on sick leave; pregnancy has, to all intents and purposes, become a justification for sick leave, despite the fact that the Social Welfare Commission's decision of 1944 (sic!) is still in force. According to that decision, pregnancy is not to be regarded as an illness since it "is related to the normal life process".21 This is a perfectly sound point of view, but one that was adopted in a completely different world from the one we are living in now and based on a completely different knowledge of and attitude to women. Pregnant women of today are unable to meet all the demands society makes on them.

The issue is acute, since the increase in the number of women taking sick leave has kept pace with the increase in the rate of female employment. Between one half and two-thirds of working women in Sweden take sick leave during the last months of pregnancy.

It is not normally possible to obtain nationwide information about the causes of absence from work in connection with pregnancy. However, in 1981 and 1987 special data searches were made for a report to the Government. The statistics show a marked shift from parent's allowances to sickness benefit. The percentage of pregnancy allowances was virtually unchanged. 81 per cent of women had received an allowance of some kind for leave of absence during the prenatal phase. The period during which allowances were paid out had also increased. 22

Several local studies have also been carried out: in 1988 the number of days of sick leave taken out in Stockholm was three times higher among pregnant women than among other women of the same age.23 Two studies carried out in Linköping and Västerås showed that sick leave during pregnancy doubled between 1978 and 1986. The trend is similar in the other Nordic countries too.

Kronoberg County Council decided to try to reverse this trend. In 1989 pregnant women were on sick leave almost three times as much as other women of the same age.26 Doctors, midwives and others were instructed to be restrictive during the last 60 days of pregnancy, i.e. the period during which mothers may be eligible for parent's and pregnancy allowances. Sick leave among this category dropped substantially in 1990, but when the figures were adjusted for the general decrease in sick leave only 1 700-3 000 kronor was saved per pregnancy. There are about 120 000 births per year in Sweden. It may well be questioned whether this is the right area in which to save on the health insurance bill, given that the number of disability and early retirement pensions is increasing and the average age of these pensioners is falling all the time. And the expenditure on such pensions, which is substantial, continues for every year up to pensionable age unlike allowances paid out during pregnancy.

Considering the high rate of sick leave among pregnant women today, pregnancy is likely to have an adverse effect on women's labour market opportunities. Pregnancy must be recognized as work that is just as valuable as any other, and that requires rest and recuperation during the last stage. However, even if this is recognized, this will not mean that all pregnant women will want or need to avail themselves of this possibility. Organizing work in such a way as to make it possible to combine production and reproduction is therefore a key issue.

The future in the mother's womb

It is not only the mothers who are especially vulnerable during pregnancy: it is also the most vulnerable period for the baby. The effects on unborn and small children can be very far-reaching, often extending to the whole of their lives.

The future is literally created, grows and is born of woman. Do we treat pregnant women as the princesses they are? No. Is this because we do not generally know enough about this vulnerable first phase of life? We know that alcohol and smoking are not good for the baby. But do we know how dangerous they can be? The fact is, we do not want to know, we do not want to face the issue. Nor do we want to know how the mother's stress affects the child, our consciences are guilty enough already...

Quantities of reports are now proving the connection between a child's pre- and postnatal period and various illnesses that occur later on in life. Can we trust these reports?

This is a very difficult field of research. A great deal of water flows under the bridge between a foetus's life in its mother's womb and the day when the same person develops cardiovascular disease 50 years later. In scientific contexts it is customary to guard against confounding factors, i.e. other explanations that may "confuse the picture". There is a tendency to seek explanations in terms of cause and effect, and the result is consequently explained by these confounding factors. Various socioeconomic factors, such as smoking and drinking, may, for example, covary with the disease in question, and in consequence it is difficult to tell to what extent the disease that appears 50 years later is attributable to these factors.

Retrospective studies are "high-risk projects". But the issue is too important to be dismissed because of this risk. At present, retrospective studies are the only option when it comes to finding the answers to these questions. Care should be taken to ensure that such studies are carried out on an ad hoc basis by researchers who are willing to take the risk of internal criticism and who have the necessary methodological competence.

The only alternative is to continue to take the short view, to bury our heads in the sand and ignore the long-term connections between mothers, children and health. This is, however, a much too risky strategy.

Sweden should be well-placed to conduct causal research on these lines in view of the unique availability of sources in this country. With our long tradition of keeping population and medical records and making them available to the public we have unique material to draw on. Data on parents' backgrounds, pregnancies, placenta weights, birth weights, birth height, breast-feeding etc. are a gold mine for researchers, even if the sources may have their shortcomings.

Mothers, children and health

During pregnancy the foetus passes through various critical, sensitive and vulnerable phases. If the unborn child is exposed to damage or a certain stimulus in the womb, its personality or susceptibility to certain diseases may be "programmed" for the rest of its life. The onset times may be long, in fact the disease may only break out at the age of fifty. Such connections have been proved in the case of some of our commonest diseases, e.g. stroke, chronic bronchitis and ischaemic heart diseases (involving a deficiency of blood due to constriction).

The child's intrauterine environment affects its future health both directly and indirectly. For example, the foetus is sensitive to intrauterine stress. The mother's infections can harm the foetus, her diet affects its future allergic reactions etc.

Although it was discovered as long ago as the 1940s that the child could be affected by the presence of the rubella virus in the mother and that the atom bombs dropped on Hiroshima and Nagasaki caused radiation sickness in foetuses, it was not until the thalidomide disaster and the Minamata disaster in Japan that the question of protecting the foetus was seriously discussed.

Today we devote a great deal of energy to adults' lifestyle factors, such as diet, exercise and smoking, in particular as a means of finding explanations for the major diseases. And when these factors have not provided sufficient evidence we use genetic and psychological explanations to fill out the picture. But the field half-way between the foetal and infant stages has long been the province of the paediatricians and has seldom been related to the disease panorama of adult life. However, there are at last signs of a breakthrough now that this vulnerable period of our lives is increasingly being included in analyses of adult diseases.

This research is extremely significant from the point of view of preventive medicine. Devoting special study to pregnant women and infants may well help to reduce the incidence of the major diseases. In other words, this research field has far-reaching implications for public health. At the same time, this approach is extremely rewarding: efforts made to protect the child during a limited period may have lifelong effects. Apart from this, such efforts will substantially improve the quality of life for parents and children, who both deserve a breathing-space during this vulnerable phase. This is important, particularly during recessions, when care of parents and children are a favourite target in the general search for ways of saving money.

Are the major diseases predestined by life in the womb?

David Barker, a British epidemiologist, is one of the few researchers who have taken an interest in onset times and the long-term effects of the foetal stage on adult health. His research has shown variations in maternal and infant mortality between different parts of England 60 or 70 years ago and that a map indicating the areas of high mortality in cardiovascular disease, chronic bronchitis and stroke today is similar.27 The areas where maternal and infant mortality was highest are also the areas where the mortality caused by the above diseases is highest today. Since the time factor is crucial in this connection, infant mortality, i.e. mortality during the first year per thousand births must be defined more precisely. Infant mortality is therefore divided up into perinatal mortality (stillbirths and deaths during the first week), neonatal mortality (deaths during the first 28 days) and post-neonatal mortality (deaths occurring after the 28th day and up to the end of the first year).

Thus Barker claims that both ischaemic heart diseases, hypertension, chronic bronchitis and stroke are related to the conditions of life during the foetal stage and infancy. The patterns vary a little between the three groups of diseases. Stroke is related primarily to early neonatal mortality, which would suggest that the main factors are associated with pre-pregnancy and pregnancy. Chronic bronchitis is related primarily to post-neonatal mortality, which indicates that the conditions during the first year, e.g. early infection risks, play an important part, while ischaemic heart diseases seem to be related to the living conditions of the mother and the baby.

Obviously, the foetal stage and infancy are not the only factors associated with a complex group of diseases such as cardiovascular diseases. The long-term trends as regards these diseases vary too. As mentioned earlier, the incidence of chronic bronchitis and stroke has diminished continuously during the last 40 years in many Western countries, while ischaemic heart diseases have become more common. This suggest that the causes are to be found in a combination of early effects and subsequent factors.

The mechanisms underlying these covariations may be regarded as a response to intrauterine stress. In other words, the foetus suffers from stress, and this leads to a redistribution of its resources to vital organs such as the brain, heart and adrenal glands at the expense of other, less vital organs. This results in permanent morphological and functional changes in the vascular system, which increases the individual's vulnerability and the risk of high blood pressure and cardiovascular disease later in life when these systems are less dynamic, in other words in middle age.

What is it in the mother's life that creates this stress in the foetus? The mother's inappropriate diet, high blood pressure, smoking, alcohol, drugs, high stress hormone levels and infections, among other things.

Diet is a recurrent theme of many of the studies in this field. Studies of the effect of different types of diet on premature babies have yielded the conclusion that the child's diet during its first few months after birth has a decisive influence on its development and growth and on the risk of subsequently developing allergies. The theory that damage during some sensitive periods of a small child's life can cause permanent changes in the vascular system has also been confirmed by studies of the effects of diet on premature babies.28

Experiments have also shown that nutritional deficiencies during the foetal stage and infancy can cause early programming, which affects the organism permanently.29

Mothers and children were involuntarily exposed to such "experiments" in connection with the German blockade of Arnhem during World War II. This caused a virtual famine. Almost 60 years later, it has been established that the women whose mothers were starved during pregnancy now give birth to children with inhibited intrauterine growth. Thus, not only the mother and child are affected, but also future generations.30 The mind boggles! What will be the effects of the famines afflicting the third world?

We still do not know what is the ideal diet during childhood to prepare us for life as adults. Perhaps it is more difficult for children who have been brought up on a low-calorie and low-fat diet to adjust to a high-energy diet than those who are used to such a diet from the start. If that is the case, when are these patterns established?

Perhaps human beings are particularly sensitive to rapid fluctuations between low- and high-calorie diets? Are we calibrated as embryos or during early childhood? If that is the case, we can expect an increase of coronary heart disease, adult diabetes and other diseases in countries that move from poverty to prosperity; this situation should stabilize after a generation or two.

The question was put a long time ago by René Dubois, a legendary biologist of the period between the wars and after the last war, whether both adult diabetes and other diseases were caused by the human organism's adjustment to very erratic energy flows.31 He considered that the high and uniform energy intake in modern society was to blame for many of our commonest diseases, which have come to be called the diseases of affluent or civilized society.

But when it comes to the foetal stage and infancy there is a great deal of evidence of the importance of nutrition. Although we know a great deal about the importance of diet for adults, we still know very little about the nutritional needs of foetuses and new-born babies. Some of these needs are satisfied by the body itself. Cholecystokinin is a hormone excreted by mothers in connection with childbirth and breast-feeding. It enables the mother to absorb food better during this phase.

But the diet of many small children in Western societies contains insufficient fat; they are served a diet that is too "nutritionally correct". And even in a country like Sweden there are still babies who starve. In Lövgärdet, a residential district outside Gothenburg, some nurses at the child care clinic have performed a pioneering study in an attempt to reverse the trend.

They found that about one new mother in five visited the clinic to get help for their baby's slow increase in weight. In many homes in the area there were no special arrangements for meals or sleep for the babies. They had to adjust to the grown-ups' way of life. The situation was especially serious in three groups: very young mothers of below average intelligence with a vulnerable social status, immigrants and refugees. They all knew too little about a child's need of proper food.

- The problem in these families is not immediately apparent. Their children often have very pretty clothes and the latest and most expensive prams. But if you look closer you can see a child sucking a bottle containing coca cola, and under the pretty clothes their hygiene often leaves a great deal to be desired, says one of the nurses in the project.32

Nutritional deficiencies are thus not only a third-world problem. And the conditions that previously prevailed in our part of the world still affect us today, just as the situation for babies today will affect the next generation.

The classic Whitehall study, which indicated great differences in the UK, also drew attention to the importance of conditions during childhood. It showed that there was a correlation between shortness of stature and high mortality in coronary heart disease, regardless of socioeconomic groups or conditions of work.33 Shortness of stature is a good indicator of low nutritional status in early life. In his study of heart disease and childhood conditions in Norway Axel Forsdahl shows how geographical differences with respect to coronary heart disease (CHD) covary with those for infant mortality 50 years earlier.34 These studies indicate that pregnant women's conditions of life affect the foetus and lead to cardiovascular disease 50 years later.

This reminds me of the first efforts to provide maternity care - the "Milkdrop Association" and other associations that provided dietary supplements for poor mothers - that emerged in Europe in the early years of this century in the struggle against tuberculosis. Perhaps they helped to reduce the mortality caused by cardiovascular disease 50 years later? That is an interesting hypothesis that has never been tested. Perhaps it is time to revive such programmes, bearing in mind the example of Lövgärdet mentioned above.

The correlation with high blood pressure is also remarkable. If the foetus is threatened by harmful or unfavourable conditions, its blood pressure may rise, as a way of ensuring short-term survival, albeit at the expense of long-term survival.35 A drastic remedy, indicating that blood pressure is calibrated for each individual during the intrauterine period.

Several studies have shown a negative correlation between blood pressure and birth weight, but a positive correlation with placenta weight.36 Perhaps this explains the correlation that has been established between stroke, ischaemic heart diseases and high blood pressure. The Hertfordshire study seems to confirm this.37

Ever since 1911 accurate data have been recorded on the birth weight of all children born in Hertfordshire. All new-born babies were observed throughout infancy by means of regular visits from nursing staff. Unfortunately, for some reason only boys were examined, a total of 5 225 grown men today. A follow-up study covering 20 000 individuals, this time both male and female, has now been launched.

The first study indicated a number of interesting correlations between birth weight and cardiovascular disease. Those who had the lowest birth weight and low weight at the age of one also suffered the highest mortality due to cardiovascular disease.

A careful follow-up was conducted on men in the age group 59-70 who were still alive in 1989. There was also a proven correlation between low birth weight and glucose intolerance and certain forms of diabetes.38 Low birth weight and low weight at the age of one increased the tendency towards abdominal obesity in adult males, which is assumed to be a risk factor for cardiovascular disease in men.39 The message of the study is clear: there is a direct correlation between many of the physiological variables that increase the risk of cardiovascular disease and low birth weight and low weight at the age of one.

It is also important to distinguish between different types of slow growth. If this takes place during the initial phase of pregnancy, the child will be symmetrically small. If it occurs later during pregnancy, the child's weight and height may be reduced, but usually not its head, i.e. the child is asymmetrical. A nutritional deficiency towards the end of pregnancy results in a thin child of normal height and head size.

If the mother smokes during pregnancy, this increases the risk of giving birth to an asymmetrically small baby, since the effects last for a long time. Mothers who smoke also have a relatively large placenta, but the number of cells is smaller than in a normally developed placenta.40

Apart from genetic factors, various environmental factors affect the development of the immune system. Various nutritional deficiencies in the placenta hamper a proper immunobiological development. Small babies initially have an impaired immunocompetence. Animal experiments indicate that this condition may be permanent, although we do not know for sure. In the case of certain infections, such as rubella, immunocompetence is permanently impaired.

The development of the various organs is critically dependent on precise timing and on a series of cell divisions in which each phase builds on the preceding one. Agents such as viruses can harm this delicate process, as is the case with rubella, which causes deafness, heart damage, impaired metabolism, diabetes mellitus etc.

The theory that early infections may start processes whose consequences only appear much later in life may be crucial to an understanding of the aetiology of some diseases in adults. These consequences are also important in terms of preventive medicine. Perhaps we should take a much more serious view of early infections, lung infections in particular, such as colds? Preventing lung infections during the first two years might reduce the risk of serious lung diseases later in life.

Smoking not only impairs the baby's immunological defence. Carbon monoxide, the poisonous gas inhaled by the mother, takes the place of some of the oxygen in the blood. The foetus takes up twice as much carbon monoxide as its mother and it remains in the foetus's blood much longer than in that of its mother. If the mother smokes several cigarettes a day, the foetus will continuously have carbon monoxide - the same gas that is emitted in car exhausts - in its blood.

Furthermore, nicotine reduces the blood flow to the child, reducing the supply of oxygen and nourishment. This can be immediately life-threatening. It is estimated that between 50 and 100 children die in Sweden every year at childbirth as a result of their mothers' smoking. Perinatal mortality (stillbirths and deaths during the first week) is 50 per cent higher where the mother is a smoker than otherwise, and the risk of miscarriage is twice as great.41 There is also a greater risk of colic, allergies, asthma and slower mental development.42

As regards allergies, there is also a connection between genetic vulnerability, nutrition, the immune system and foetal development. Mothers with an increased risk of allergy in their family should keep to a strict diet during pregnancy and breast-feeding and avoid well-known allergenic food products, and they should also try to prolong the breast-feeding period. This is a very important factor in reducing the risk that the child will develop allergies in the future. In view of the widespread incidence of allergies in a country like Sweden - one adult in four, and one schoolchild in three, suffers from some allergy, which means that over two million Swedes have or have had an allergy problem - the mothers' conditions of life are crucial to a reduction of the future incidence of allergies.43

Intrauterine stress

If the difference between the demands made upon us and our own capacity is too great, our response is stress. Strictly speaking, stress is an instinctive reaction to a dangerous situation. Our muscles, heart, lungs and brain are given priority, while the rest of our body takes a back seat. The production of the stress hormones adrenalin, noradrenalin and cortisol increases dramatically. Adrenalin speeds up the pulse, but it also reduces the supply of blood to internal organs, including the placenta, so as to provide more blood for the muscles. Noradrenalin contracts the blood vessels, thus increasing the blood pressure. Cortisol affects the metabolism of various nutritious substances. When we are subjected to changes which we are unable to do anything about we suffer stress. The life and work situations of many women present great demands and little scope for meeting them. Such stress situations have been regarded as one of the reasons for the increase in the number of premature births. One midwife has even warned that this represents a life-threatening trend for foetuses.44

We still do not know what will be the effects of today's very low birth weights in conjunction with premature deliveries, but there is nothing to suggest that they are likely to cause permanent damage of the kind discussed above. The causes in those cases are quite different from those that are responsible for low birth weights in fully-developed babies. 45 Today's high percentage of premature babies may be due to a change in timing due to changed conditions of life in modern society.

Alan Lucas of Dunn Nutrition in the UK has made a special study of programming as a result of early nutrition. He points out that today various processes during pregnancy appear to start earlier than they should "according to the timetable":

"Whole systems are operating in an unusual way: the cardiovascular system moves into postnatal mode from fetal mode months too soon. So the premature baby is perhaps a good model for investigating what happens when switches are thrown at the wrong time."46

Many children are born small as a result of intrauterine stress. For ethical reasons we cannot carry out controlled studies on pregnant women. But similar studies performed on animals can tell us about the mechanisms at play here.47 Rhesus monkeys are interesting in this context. Their period of gestation is similar to human pregnancy and their hormone system is very similar to that of humans too. Controlled experiments on rhesus monkeys have shown that hypoxic stress (lack of oxygen) leads to a substantial increase in the foetus's blood pressure, while the action of the heart slows. The volume of blood is redistributed in the body so that the heart and the brain are given preference over other organs, such as the kidneys and intestines.

This reaction may be necessary for immediate survival, but what are the long-term effects of the reduction of the blood supply to these organs? Is there permanent damage? The fact is that we do not know exactly what happens in stress situations. However, it has been established that the levels of catecholamine (a stress hormone) are significant.

It seems that in a crisis the placenta gives preference to its own growth and functional needs rather than those of the foetus, since a functioning placenta is the first priority, without which the foetus cannot survive anyway. This redefinition of priorities must therefore be regarded as a matter of first line survival defence for the foetus.48

The importance of the size of the placenta is disputed. Some studies indicate a negative correlation between the size of the placenta and various deficiencies, while others indicate the reverse. The wisest course is probably to wait and see. There is a great temptation to use methods that ensure ease of measurement for processes that are extremely complex. For example, the weight of the placenta depends on how much blood has been squeezed out of it first. A few years ago there was much discussion of the "working woman's syndrome". It was assumed that the stress under which such women lived would cause calcification of the placenta. A veritable measuring hysteria, backed by numerous studies, has not resulted in any conclusive evidence.

Various stress hormones may be present in the placenta and affect the foetus's immunocompetence. It has been shown that stress caused by starvation impairs the production of antibodies, not only by the foetus but also in the following generation. As regards malnutrition, the first six months of the baby's life also seem to be significant,49 while malnutrition at a later stage only has a temporary effect on immunity.

Early development of the brain

As regards the early development of the brain, there are known to be certain critical periods ("windows") during which the foetus is particularly vulnerable.50

We know that hormones partially determine the structure of the brain and our behaviour. Animal experiments in which the foetus's brain was exposed to varying doses of sex hormones at critical times led to fundamental, lifelong changes of behaviour.

The child's sex is determined not only by the individual's genotype,51 but also by hormonal influence during the foetus's sixth week. At this stage either the cells that produce male hormones, testosterone in particular, develop or, if this does not happen, the foetus will be female. This means that the brain is originally female. Very high momentary doses of male hormones are needed to form male genital organs and also to influence the brain. If the hormone levels excreted during this phase are insufficiently high, male genital organs develop, but the brain remains "female". Correspondingly, a female foetus exposed to a dose of male hormones may develop a male brain in a female body.52 The Canadian psychologist Sandra Witleson came to the conclusion, on the basis of the findings of brain research during the last few decades, that "the brain is a genital organ".53 Obviously this is a very sensitive subject, but we must nevertheless study the results of neurobiological research in order to establish the potential consequences.

Generally speaking, there are certain differences between men's and women's brain functions. Many characteristics are, in purely physiological terms, specifically located in the male brain, e.g. spatial capacity. In the case of women these characteristics are controlled by centres distributed in various parts of both hemispheres. The differences in the structure of the brain affect men's and women's way of thinking. The specialization of the male brain leads to better results in mathematical and spatial tests, e.g. map reading.54 On the other hand, verbal ability and certain linguistic skills such as spelling, writing and grammar are more specifically located in the female brain, as a result of which women's linguistic skills are superior. Dyslexia, for example, is four times as common among boys as among girls, and it is common knowledge that girls generally learn to talk earlier than boys.55 These differences may be observed in many different cultures.56

Women have more nerve-paths between the cerebral hemispheres and some parts of their cerebral cortex are thicker, which allows larger amounts of information to be transmitted between the hemispheres.57 Perhaps this explains women's greater sensitivity to sensory impressions and their ability to communicate and process several social events at the same time. Women hear better than men and are more sensitive to sound. They also have a broader field of vision, better developed peripheral vision and better twilight vision due to a larger number of cones and rods in their eyegrounds. They are also more sensitive to pain and have a stronger sense of smell and taste.

Men, on the other hand, find it easier to see patterns and understand abstract relations. Their hand and eye coordination is also much better. Memory also distinguishes the sexes. Women can store more information, including apparently incoherent information, for short periods, while men have to structure the information more clearly to be able to remember it. Obviously, there are great difference between individuals, often greater than the general differences between the sexes.58

However, the American educationalist Elisabeth Fennema, who has spent two decades studying differences between the sexes in mathematical ability, warns against drawing too far-reaching conclusions from the genetic and neurobiological research. She notes that men generally show better results in mathematical problem-solving, but points out that this may be due to the fact that the teaching of mathematics is more suited to boys than girls:

- Women generally learn better if they are allowed to cooperate, while men tend to learn better in a competitive situation. The traditional teaching of mathematics is largely based on individual work. Mathematics is a subject that lends itself to competition, even contests, says Elisabeth Fennema.59 She mentions the feministic view of mathematics, according to which there is a special female kind of mathematical logic. Mathematics is a much more complex subject than has been realized up to now, and women's thinking may develop completely new fields of mathematical study.

Therefore, there must not necessarily be a contradiction between biological research findings and the logical and learning aspects. Differences that are established at the foetal stage are accentuated by the structure of our societies. Our destiny is by no means determined by biology. The anthropologist Helen Fisher, the author of "The Anatomy of Love. A Natural History of Adultery, Monogamy and Divorce" also claims that these differences "make evolutionary sense".60

Even the celebrated female intuition can be explained in evolutionary terms. Donald Symons points out that hominid women, who could assess a personality from small clues and gestures, were eminently capable of choosing the right husband for their own survival and that of their children.61 This intuitive ability, which was noticed long ago by Charles Darwin, can now be described in physiological terms and related to the growth of the brain in the foetus:

"Women absorb cues from a wider range of visual, aural, tactile and olfactory senses simultaneously. Then they connect these ancillary bits of information giving women that ready insight that Darwin extolled."62

Thus, some of these basic characteristics are determined at the very beginning of life at the foetal stage. For example, a deviant hormonal effect can account for a girl's "male" brain structure and vice versa. The type of hormone, the dose and the timing can have a decisive effect on our personality and can explain the difference between tomboys and boys with girl's interests. This hypothesis is resolutely pursued by Ann Moir and David Jessel in their book "Brain Sex", which was referred to above, but they are not the only ones to have arrived at this conclusion. The consequences in social terms can be far-reaching: by manipulating the supply of hormones at various stages of pregnancy we can influence people's way of living and thinking by a sort of prenatal sense control.

This was done unintentionally in the 1950s and 1960s in connection with routine treatment of various risk groups of pregnant women with male or female sex hormones. In order to reduce the risk of miscarriage in women with diabetes they were treated with the synthetic female sex hormone diethylstilbestrol. The hormones altered both the brains and behaviour of the boys who were born, making them more feminine.63

In the same way, male sex hormones were administered to pregnant women who suffered from toxaemia (metabolic disturbances during pregnancy). Many of the girls who were born to these mothers developed typical male characteristics.64 But these effects depend not only on the hormone that is administered and the dose, but also at what time. When this time has passed the brain is resistant to new doses owing to a kind of immunobiological reaction. According to this theory, differences in human behaviour are attributable to the interaction between hormones and the brain.

Unusual combinations of chromosomes also provide interesting clues. Men with an extra Y chromosome (XYY) obtain better results in spatial tests than those with an extra X chromosome (XXY, Klinefelter's syndrome), although their results are poorer than those of normal boys with an XY chromosome complement.65 Girls born with a single X chromosome (Turner's syndrome) are "excessively feminine", with a complete lack of interest in sports and letting off steam but a passion for children and marriage. Unfortunately, they are invariably sterile.66

Much recent research has confirmed these findings. The question is: how does this affect us men and women as adults? Do we have the courage and energy to assimilate this new knowledge? It is, after all, distinctly unnerving to find that events that take place in your mother's womb can affect the rest of your life and even the lives of future generations. An incident that indicates that the scientific community does have such scruples is the initial refusal to pass a doctoral thesis on early imprinting on the grounds that "the scientific findings might have an impact on health care"67. But is not that supposed to be one of the driving forces behind research? This controversial thesis is of vital significance for the question of the long-term effects of pregnancy and childbirth and therefore merits more detailed comment.

Are human beings imprinted too?

In May, 1992 Karin Nyberg, a midwife at the Karolinska Institutet, defended her doctoral thesis on the long-term effects on the foetus of the treatment given in conjunction with childbirth.68 She studied whether there was any connection between the painkillers administered during childbirth and drug misuse later on in life. Her hypothesis was that our lives as adults are affected by certain stimuli - imprinting - received during a short but critical period during birth.

Imprinting is a well-known phenomenon in the animal kingdom. The classic example is the newly hatched duckling that pins its faith in the first moving object it sees, for example a shoe. Ms Nyberg's theory is that a sense of pleasure is aroused in the unborn baby, which is later fulfilled by drugs, which have the same function as the shoe for the duckling, something the person feels familiar with and places his trust in.

This is an interesting and extremely important theory, although of course it is confused by many of the factors that were discussed above, particularly in view of the alacrity with which painkillers of all kinds are administered in conjunction with childbirth. Barbiturates, opiates and laughing gas were generously administered in the 1950s and 1960s. Many women in labour were, and are still, given a pethidine injection without even asking for it. Their children are born under the influence of drugs.

Obviously, many other factors must be taken into account in connection with drug abuse, e.g. the childhood environment, the family, conditions at home and school, biological damage and genetic constitution. To make as much allowance as possible for these factors, brothers and sisters were used as control groups so as to ensure that the family and genetic factors were as similar as possible. Karin Nyberg does not claim that these factors do not matter, she merely wishes to find out whether the drugs administered in connection with childbirth may conceivably help to explain why drugs are abused by some people but not by others.

The thesis made a great stir and was not passed. After a number of revisions of her thesis Karin Nyberg received her doctorate in medicine at the Karolinska Institutet in January, 1993. What was all the excitement about? Was the thesis inadequate from a scientific point of view? No, it was no worse than many other papers that pass as doctoral theses in the world of medicine. On the contrary, the studies included in the thesis are well-executed from a methodological point of view.

It is a classically organized scientific thesis consisting of four papers linked by a frame narrative. She used accepted scientific methods, case control studies and epidemiological methods. The studies are retrospective, with all the methodological problems that this entails. But that is certainly no reason to reject the thesis. In many research fields retrospection is the only possible method, viz. the historical disciplines. Does that mean that the research is not scientific?

Of course not; the objections related instead to the idea underlying the study, the notion that something that takes place during a short period in conjunction with childbirth can have such far-reaching consequences. This arouses resistance of an emotional kind: it simply cannot be so. And perhaps it is this resistance that makes it so difficult for us to accept the available research on the extraordinary importance of the foetal stage and infancy for adult life. Protecting and caring about mothers during pregnancy is probably one of the most important preventive measures that we can take. We need a good pregnancy culture for the sake of our common future. The future is literally created, grows and is born of woman.

NOTES

(Sw after a title indicates that the text is in Swedish)

1. According to the labour market research conducted by the National Labour Market Board (AMS) and Statistics Sweden (SCB), Sweden's workforce in November, 1993 consisted of 4.234.200 people, 51.9% of whom were men and 48.1% women. 79.1% of the male population between the ages of 16 and 64 was in employment, while the figure for women was 75.8%. For a long-term forecast see AMS, "A Changing Labour Market Policy" (Sw), Allmänna förlaget 1992 and C. Jonung & I. Persson (eds.) "The Role of Women in the Economy" (Sw), Long-Term Commission (LU), Annex 23, Ministry of Finance 1990.

2. M. Domzalska "Women in the European Community. Rapid report of Eurostat", Luxembourg, December 1993. See also I. Hedström, Dagens nyheter (DN) Dec. 2 1993, p. A 13 (Sw).

3. Due to the changes in the health insurance system it is not possible to make direct comparisons with developments in the 1990s. The "sickness index" showed a sharp rise in sickness among the elderly, but a decrease among the young in the years 1990-93. See "Development of the Sickness Index", National Social Insurance Board (RFV), current statistics from the Analysis Division.

4. B.I. Puranen "Is Women's Ill-health Due to Their Double Workload?" (Sw), Socialmedicinsk tidskrift 7-8 1991.

5. See the RFV's statistics on payments made and the number of days for which benefit was received under the care of sick children, father's day and school contact day allowances in 1992 and 1993. A comparison between the period April-June 1992 with the corresponding period in 1993 shows a decrease of 354.185 days, or 16%. See RFV, Jan. 11 1994.

6. In spring 1991 several reports were submitted. The National Board of Health and Welfare presented its Public Health Report, which confirmed the facts. The Work Environment Institute submitted a report on early retirement among women. See also DN, January 13 1991, interview with B. Puranen "Women's health deteriorating" (Sw) and the same newspaper March 8, March 23, April 24 and June 30, 1991.

7. "Women and Men in the Nordic Countries. Facts on Equality 1988". Nordic Council of Ministers 1988:58, Copenhagen 1988, p. 86 (Sw). The figures relate to 1985.

8. T. Friberg & I. Olander "Women in Gainful Employment" (Sw), ERU report 49, Stockholm 1987.

9. T. Friberg & I. Olander 1987, p. 29.

10. C. Jonung & I. Persson (eds.) "The Role of Women in the Economy" (Sw), LU, Annex 23 1990

11. C. Jonung & I. Persson 1990, p. 33ff. Relates to Sweden 1963-88.

12. H.E. Fisher "Anatomy of Love. The Natural History of Monogamy, Adultery and Divorce" Simon & Schuster, London 1992; D.J. Haraway "Simians, Cyborgs and Women. The Reinvention of Nature", Free Association Books 1991; C.G. Helman "Culture, Health and Illness", Butterworth Heinemann 1984, 2nd ed. 1990; M. French "The War against Women".

13. Y. Hirdman "Power and Sex" (Sw) in O. Pettersson (ed.) "The Concept of Power" (Sw), Stockholm 1967; Y. Hirdman "The Gender System - Reflections on Women's Social Subordination" (Sw) in KVT (9), 1988:3; Y. Hirdman "The Gender System" (Sw) in "Democracy and Power in Sweden" (Sw) SOU 1990:44, Stockholm 1990. See also R. Liljeström "The Organization of Survival" (Sw) in G. Kyhle et al. (ed.) "The Daughters of Labour 2. Sociological and historical viewpoints" (Sw), Stockholm 1986; M. Edwards & U. Mann "On Gender and Gender Systems" (Sw) KVT (8) 1987:4 and C. Holmberg "A Thing Called Love" (Sw), thesis, Anammas förlag 1993.

14. C.G. Helman 1990, p. 127.

15. Y. Hirdman, p.70 and C. Holmberg 1993, p.70.

16. A. Strindberg "The Father" (Sw), Helsingborg 1887, p. 67.

17. H. Fisher 1992, p.198

18. H.C. Östgaard "Back Pain and Pregnancy", Gothenburg University, 1991 (thesis) and B. Källén "Epidemiology of Human Reproduction" CRC Press Inc 1988.

19. J.L. Harris & E.C. Davidson "Sociologic Aspects of Pregnancy" Curr. Opin. Obster. Gynecol., 1992, Dec. 4(6):797-801; G. Chamberlain "ABC of Antenatal Care. Work in Pregnancy" British Medical Journal. May 4 1991:302:67841, pp.1070-1073; T.V. Persaud "The Pregnant Woman in the Work Place; Potential Embryopathic Risks" Anat Anz 1990, 170(3), pp.295-300; A.S. Röcklinger et al. "Women Should Be Granted Leave during Pregnancy Without Having to Take Sick Leave" (Sw), Läkartidningen, vol. 89, no. 21 1992, p. 1882-1884.

20. See for example R. Edström "The Work Environment and Foetal Damage" (Sw), Nat. Board of Board of Occupational Safety and Health 1986; P. Westerholm "Pregnancy and the Work Environment" (Sw) 1993; K. Søgaard "Pregnancy and Sedentary Work: Work Environment Fund working party report" (Danish), Copenhagen 1987.

21. A.S. Röcklinger et al. 1992, p.1882.

22. National Social Insurance Board: Examination of Pregnancy Allowance Cases" (Sw), report to the Government, RFV 1988:4.

23. Stockholm County Social Insurance Office "MOR 88. An Investigation of Pregnant Women's Sick Leave etc." (Sw), Stockholm 1990, unpublished.

24. A. Sydsjö et al. "High Absence from Work during Pregnancy Despite a Well-developed Health Insurance System" (Sw), Läkartidningen, vol. 86, no. 47,1989, pp.4141-4144.

25. Nordic Council of Ministers "Perinatal Care in the Nordic Countries, Checks of Pregnant Women, Pre- and Neonatal Care" (Danish), Dike/Munsgaard, Copenhagen 1986. See also E. Wergeland et al. "Pregnant in Norway in the Early Nineties" (Norwegian). Pregnancy and Work. Report no. 1. Oslo University, Departmental Group for Social Medicine, Oslo 1991, unpublished.

26. A. Håkansson "General Pregnancy Allowances. New Sick Leave Policy Reduces the Number of Pregnant Women on Sick Leave" (Sw), Läkartidningen, vol. 90, no. 28-29 1993, pp 2543-2546 and E. Thorén et al. "Introduce Two Months´ Universal Pregnancy Allowance" (Sw), Läkartidningen, vol. 89, pp.3851-3854.

27. D.J.P. Barker "Fetal and Infant Origins of Adult Disease", British Medical Journal 1992 and the same author's "The Intrauterine Environment and Adult Cardiovascular Disease" in G.R. Bock & J. Whelan (cd) "The Childhood Environmental and Adult Disease" Ciba Foundation Symposium 156, John Wiley & Sons 1991, pp.3-16.

28. A. Lucas "Programming by Early Nutrition in man" in G.R. Bock & J. Whelan 1991, pp.38-55.

29. Ibid.

30. L.H. Lumey "Obstetric Performance Of Women After In Utero Exposure to the Dutch Famine (1944-1945)", Columbia University 1988. Diss, UMI diss Services no 8827610.

31. R. Dubois 1990.

32. E. Magnusson "Pioneer Work Among Young Mothers Impoortant for the Children's Future" (Sw), Landstingsvärlden no. 5 1992, pp. 16-17.

33. The Whitehall study.

34. A. Forsdahl "Are Poor Living Conditions in Childhood and Adolescence an Important Risk Faktor for Arteriosclerotic Heart Disease?", British Journal of Medicine.

35. D.J.P. Barker 1992, pp.165-206 and D.J.P. Barker, p.7.

36. D.J.P. Barker 1992, ch. 16, 17.

37. D.J.P. Barker 1991, p.3 ff.

38. D.J.P. Barker 1992, ch. 22.

39. Ibid., ch. 26.

40. S.W. D'Souza et al. "Smoking in Pregnancy: Associations with Skinfold Thickness, Maternal Weight Gain, and Fetal Size at Birth" Br. Med. J. 1981, 282, pp.1661-1663 and J. Wingerd et al. "Placental Ratio in White and Black Women; Relation to Smoking and Anemia" Am. J. Obstet. Gynecol, 1976, 124, pp.671-675 and K.L. Thornburg "Fetal Response to Intrauterine Stress" in Bock & Whelan 1991, Discussion, p.33.

41. "Smoking and pregnancy", Journal of Psychoactive Drugs 1984; 16, pp.327-338; M.B. Meyer & J.A. Tonascia "Maternal Smoking, Pregnancy Complications and Perinatal Mortality" American Journal of Obsterics and Gynecology". 1977, 128, pp.494-502.

42. WHO: "Women and Tobacco", Geneve 1992; P. Frogatt "Smoking and Health", Further Report of the Independent Scientific Committee, London, HMSO and Royal College of Physicians, M. Plant & M. Plant "Risktakers. Alcohol, Drugs, Sex and Youth", Tavistock/Routledge 1992, p.84; R.L. Naeye & E.C. Peters "Mental Development of Children Whose Mothers Smoked During Pregnancy", Obstetrics and Gynecology, 1984;64 pp.601-607; N.R. Butler & H. Goldstein "Smoking in Pregnancy and Subsequent Child Development", British Medical Journal, 1973;4, pp.573-575.

43. "Report of the Allergy Commission" (Sw), SOU 1989:76, Stockholm 1989, p. 30.

44. "The greatest threat to natural pregnancies is stress", says L. Hallin, see I. Eding "There Is More to Maternity Care than Wombs!" (Sw), interview with L. Hallin, Kvinna Nu, no. 2, 1993, p. 30.

45. D.J.P. Barker 1992, chapter 28.

46. G.R. Bock & J. Whelan 1991, General Discussion, p.229.

47. K.L. Thornburg 1991, p.17.

48. Ibid.

49. R. K. Chandra "Interactions between Early Nutrition and the Immune System", in G.R. Bock & J. Whelan 1991, pp.77-92 and W. Dutz et al. "Persistent Cellmediated Immune Deficiency Following Infantile Stress During the First 6 Months of Life" Eur. J. Pediatr. 122, 1976, pp. 117-126.

50. J.L. Smart "Critical Periods in Brain Development" in G.R. Bock & J. Whelan 1991, pp.109-124.

51. Male foetus XY, female foetus XX. Half of our chromosome pairs come from our mother and half from our father. The last pair differs from the others: the mother contributes an X chromosome and the father a Y chromosome.

52. See R.W. Goy & B.S. McEwen "Sexual Differentiation of the Brain", MIT Press, Cambridge Mass., 1980 and C.M. Otten "Genetic Effects On Male and Female Development and on the Sex Ratio" in R.H. Hall et al. (eds.) "Male Female Differences: A Bio-Cultural Persective", New York, Praeger 1985. For obvious reasons most of the experiments were performed on animals; one of the more interesting is A. Jost "A New Look at the Mechanisms Controlling Sex Differentiation in Mammals" John Hopkins Medical Journal 130, 1972, pp.38-53, Otten 1985.

53. S. Witleson et al. "The Hormonal Control of Sexual Development", Science; 211, 1981, pp.1278-84 and the same author's "Sex Differences in the Neurology of Cognition; Social, Educational and Clinical Implications" in E. Sullerot (ed) "Le Fait Féminin Fayard, Frankrike, 1978. See also A. Moir & D. Jessel "Brain Sex", Mandarin, 1989 p.28.

54. E. Fennema & C.G. Leder (eds.) "Mathematics and Gender", New York, Teachers College Press, 1990. See also C.G. Leder "Gender Differences in Mathematics: An Overview" in E. Fennema & C.G. Leder 1990.

55. E.E. Maccoby & C.N. Jacklin "The Psychology of Sex Differences" Stanford University Press, 1974; D. McGuinnes "Perceptual and Cognitive Differences between the Sexes" in B. Lloyd & J. Archer "Explorations in Sex Differences", New York, Academic Press, 1976; "Sensory Biases in Cognitive Development" by the same author in R.H. Hall et al. (eds.) "Male-Female Differences: A Bio-Cultural Perspective", New York, Praeger 1985; D. McGuines & K.H. Prilbram "The Origin of Sensory Bias in the Development of Gender Differences in Perception and Cognition" in M. Bortner (ed) "Cognitive Growth and Development", New York, Brunner, 1979.

56. D. McGuinnes "Sensory Biases in Cognitive Development" in R.H. Hall et al. (eds.) "Male-Female Differences: A Bio-Cultural Perspective", New York, Praeger, 1985 and C.G. Lender "Gender Differences in Mathematics. An Overview" in E. Fennema & C.G. Leder (eds.) "Mathematics and Gender", New York. Teachers College Press, 1990. Benderly 1987.

57. C. Delacoste-Utamsing & R.L. Holloway "Sexual Dimorphism in the Human Corpus Callosum", Science, 216, 1982, pp.1432-1432 and D. Kimura "Sex differences in Cerebral Organization for Speech and Practice Functions", Cardinal Journal of Psychology, 37, 1983, pp.19-35;1 and D. McGuinnes 1985.

58. B.L. Benderly "The Myth of the Two Minds: What Gender Means and Doesn't Mean", New York Doubleday 1987 and the same author's "Don't Believe Everything You Read: A case study of how the politics of sex differences research turned small finding into a major flap", Psychology Today, Nov. 1989, pp.63-66.

59. Svenska dagbladet, Oct. 11 1993, Eva Bäckstedt's article on Elisabeth Fennema (Mathematics and Girls). See also E. Fennema & C.G. Leder (eds.) "Mathematics and Gender", New York, Teachers College Press, 1990, See also C.G. Lender "Gender Differences in Mathematics. An Overview" in E. Fennema & C.G. Leder 1990; cf. J. Sherman "Sex-Related Cognitive Differences: An Essay on Theory and Evidence", Springfield, III, 1978; cf. B.L. Benderly 1987, who is critical of the findings.

60. H.E. Fisher 1992, p.194.

61. D. Symons "The Evolution of Human Sexuality", Oxford University Press, 1979 and D. Symons & B. Ellis "Human Male-Female Differences in Sexual Desire" in A.E. Rasa et al. (eds.) "The Sociobiology of Sexual and Reproductive Strategies", New York, Chapman and Hall 1989.

62. H.E. Fisher 1992, p.195.

63. A. Moir & D. Jessel D. Kimura "How Sex Hormones Boost or Cut Intellectual Ability", Psychology Today, Nov. 1989, pp.63-66.

64. D. Kimura 1989; Moir & Jessel 1989.

65. Longitudinal studies have now been made in which XXY boys were observed throughout childhood. They have inferior language skills, slower neurological development and learning problems. See M.W. Mandoki et al. for a review of existing research, "A Review of Klinefelter's Syndrome in Children and Adolescents", J. Am. Acad. Adolescence Psychiatry, 1991, May 30;3 pp.167-172. K. Sörensen "Physical and Mental Development of Adolescent Males with Klinefelter's Syndrome", Horm Res 1992;37, Suppl 3, pp.55-61; J. Nielsen & M. Wohlert "Sex Chromosome Abnormalities Found Among 34.910 Children; Results from a 13-Year Incidence Study in Århus, Denmark", Birth Defects 1990;26(4), pp.209-223.

66. A. Swillen et al. "Turner's Syndrome. A cross-sectorial study of 50 pre-adolescent and adolescent girls", Genet Couns 1993;4(1), pp. 7-18; J.L. Roos et al. "Neurocognitive Function and Brain Imaging in Turner's Syndrome. Preliminary Results" Horm Res 1993, 39, Suppl 2, pp. 65-69; Otten 1985.

67. K. Nyberg, "No Legal Rights for Doctoral Candidates. Should Have Right of Appeal" in Theme: Thesis at the Centre of a New Debate on Principles" (Sw), Läkartidningen, vol. 90, no. 10 1993, p. 969.

68. K. Nyberg, "Studies of Perinatal Events as Potential Risk Factors for Adult Drug Abuse", Karolinska Institutet, Stockholm 1993.

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