Birth Weight: It's Critical Importance
My mother, who is now in her 90s, tells me that when she was young people thought you were the way you were and there was not much that you could do about it. So that thin people were thought to be that way as a consequence of their constitution and conversely overweight people were also accepted as inherently being that way.
The fact that such people could be blamed for their health status is apparently a relatively recent concept. And, although we have all grown up in a world where the mantra of diet and exercise is constantly repeated, it has made surprisingly little impact on health, weight or mortality statistics.
The other assumption of recent decades has been that if it is not lifestyle factors at fault, then genetic analysis would provide the answers we seek. However, the genes for many of the diseases that most trouble mankind have failed to materialise, and in any case, there is no reason why such genes should exist or have persisted.
The work of the last two decades of Professor David Barker of the University of Southampton, UK, and his research team has shed an intriguing new light on this problem. Now known as the Barker Hypothesis his work is covered in a documentary which is available to view on this site (see Further Resources below).
The Barker Hypothesis
A former general medical practitioner, David Barker wondered about all this too and made a correlation between birth weight and its lifelong consequences which might seem to support the view held in the early part of the twentieth century. This theory represents a paradigm shift and in the eyes of many appears too simple to be true.
With twenty years of research involving tens of thousands of people however, his controversial theory seems to be holding up for people all over the world from both developing and industrialised countries. What it maintains is that your birth weight is an accurate predictor of your future mental and physical health, and lifespan. And this has been found to be true across the whole spectrum of birth weights so that a 7 lb baby has better prospects than a 6 lb baby, and an individual that weighed 9 lb at birth is more robust than one that weighed 8 lb.
This theory suggests that the first nine months of your life in the womb programmes the rest of your life and that we are effectively dealt our constitutional hand at birth. Those with strong constitutions appear to be pretty resistant to environmental influences whereas for others with weak constitutions, optimising environmental factors such as exercise and nutrition will prove critical to their health and wellbeing.
The Barker Hypothesis is strongly supported by numerous studies in animals and although it would be unethical to conduct any prospective study into the effects of deprivation during pregnancy in humans, the Dutch famine of 1944 provided a real-life study. At the time, the Nazis were retreating and had commandeered all the food in Holland and banned the transport of any foodstuffs. The whole nation was starving for a period of 5 months surviving on an average of 2 potatoes, 2 slices of bread and a sugar beet each per day. This amounted to just 400 calories each daily and was obviously nutritionally very deficient.
A Dutch researcher managed to trace 2,000 of those individuals whose mothers had been carrying them during the famine and found them to have elevated rates of heart disease, hypertension, raised blood cholesterol, type II diabetes and breast cancer. They were much less healthy than their brothers and sisters born after the famine in spite of sharing the same genetics and home environment.
Also, although men continue to make sperm throughout life, a woman is born with her lifetime quota of eggs in her ovaries. This means that the eggs that are destined to become her grandchildren were formed when she was pregnant with her own daughters. This suggests that the effects of nutrition during pregnancy may last for at least two generations. So that low birth weight babies born prematurely, or to smokers or drug addicts may have lifelong health problems and also that there may be generational consequences for such children.
In particular, the mother's nutritional status at conception and during the first 12 weeks of pregnancy appear to be critical and this is because the foundations for all the organs are being laid down at this time. Although nutrition cannot change our genes, it can alter their expression and these genes will be subsequently be expressed in every cell in the child's body.
The huge class divides in health status and longevity which even socialised medicine and vigorous public health campaigns have failed to impact may be due, in fact, to generational under nourshment and specifically malnutrition during pregnancy.
Diabetes
Type II diabetes has always been regarded as being a disease relating to affluence, overconsumption, obesity and lack of exercise, but it has recently been rapidly increasing among deprived, poor and malnourished people especially in India. This is in spite of the fact that these villagers eat a vegetarian diet, drank little if any alcohol, do hard physical labour, walk long distances and are either slim or underweight.
A team of researchers in rural India have been monitoring 200 individuals that were born 21 years ago taking regular measurements and blood samples which they have been testing for insulin resistance. What they have found is that low birth weight was linked to growing insulin resistance which was evident at 4 years of age and that by 21 years of age the subjects' blood glucose levels had started to rise - an early sign of type II diabetes.
Also, although the Indian villagers appear to be slim, analysis of their body composition reveals that they have a much higher percentage of body fat than occurs in Caucasian people of similar size and weight. The researchers refer to these people as being 'thin fat' people and this high proportion of body fat is evident from birth.
The critical factors during pregnancy do not appear to be related to total calories, protein or fat but to the micronutrients present in leafy green vegetables, fruit and milk. So that if the mother is low in vitamin B12 and high in folate then she will give birth to a 'thin fat' baby who is likely to go on to later develop type II diabetes.
Prospective studies are now being conducted in the slums of Mumbai into the effects of providing a micronutrient rich diet prior to conception and during pregnancy to see whether this holds the potential to alter the fates of these children.
Cardiovascular disease
The rates of cardiovascular disease among the Indian villagers is also very high in spite of the fact that they should be 'low risk'. However, some of the 21 year olds being monitored by the study are already showing signs of arterial plaque formation.
Historically, development of the heart was always thought to be prioritised during foetal development. When the foetus is in the womb, the heart has to pump blood against the blood vessels in the placenta and the pressures against which it has to work shape the size of the heart chambers and the thickness of its muscular walls for life. The mother’s nutrition is thought to be critical in development of the placenta and this in turn determines the health of the baby's heart.
At birth the heart is almost complete and it will only enlarge as the body grows. If the mother is undernourished during pregnancy, then heart development speeds up, possibly in preparation for an early birth. But this leaves a heart with a smaller number of muscle cells, and a diminished reserve for repair in later life.
The role of elevated blood cholesterol levels in heart disease has also been revealed by these studies. Cholesterol is an important component of cell walls and the majority is not eaten in the diet but made by the liver. Measuring the girth of new borns gives an indication of the relative size of the liver and this acts as a measure of the extent to which the undernourished foetus has traded off liver growth to protect brain growth.
These girth measurements have been found to be an accurate predictor of blood cholesterol levels sixty and more years later. With the greater the size of the liver at birth being related to lower blood cholesterol levels and the smaller, less well developed liver at birth being related to future elevated cholesterol and heart disease.
Animal studies have confirmed that is it is easy to permanently alter future liver function by changes to the pregnant mother’s diet and that this alters the balance of the liver’s specialist cells.
Hypertension too is thought to relate to the lifelong reduction in the total number of nephrons in the kidneys in lower birth weight babies. During gestation the kidneys are not essential because the mother's body via the placenta is working to excrete toxins. So that development of the kidneys may be regarded as being secondary to development of more important organs such as the brain in the womb.
The development of hypertension and elevated cholesterol levels in the offspring can be induced in experimental animals by manipulating the diets of the mothers during pregnancy.
Personality
Our personalities too may also be much more predetermined than we have previously been led to believe. Even in the womb, some foetuses are more reactive to stimuli than others. Our ability to recover and regulate our system after an upset is considered a core feature of temperament.
It appears from studies conducted on foetuses that some are more easily startled and find it harder to cope with emotional and physiological stress than others and this appears to be a consistent component of their temperament throughout life.
In addition, all foetuses start out as female until the male sex hormone, testosterone, causes male foetuses to masculinise. MRI scans of children are revealing that development of part of the corpus callosum that connects the two brain hemispheres depends upon testosterone and that it is bigger on the left than on the right with low testosterone levels. This may relate to the later ability to read emotions and map reading which have been shown to be related to in utero testosterone surges. Higher testosterone levels in the womb have also been shown to produce tomboy girls who prefer playing with boys' toys.
The role of the placenta and gender
Male foetuses grow more rapidly than female foetuses - even before implantation and this makes them more vulnerable if their nutrition is compromised. This is reflected in the higher risks associated with carrying a boy who are more likely to have placental abnormality, retarded growth, or die during the perinatal period. In the Dutch famine, the number of boys born fell in relation to the number of girls.
The nutrition of a foetus depends on various aspects of the mother’s nutrition, including her diet, her nutritional stores and her metabolism, which is in turn the product of her lifetime’s nutrition.
The role of the placenta in being able to efficiently deliver the nutrients the mother consumes to the child is also critical and this is reflected in its size. The blood of the mother and the foetus interface but do not mix and toxins and nutrients are exchanged from mother to foetus across this placental barrier.
Small babies generally have small placentas. Mothers who smoke during pregnancy both reduce the size of the placenta and also increase the barrier between the blood of the foetus and mother.
At the same birth weight, boys are longer, have larger heads and are thinner than girls. Which suggests that male babies may trade visceral development in order to protect brain growth. Male foetuses also prioritise brain development over growth of the placenta and this risky strategy may result in more malnutrition in boys.
The placentas associated with male foetuses are more efficient but also may have less reserve capacity, which increases their vulnerability to under nutrition. Studies done in Saudi Arabia where the importance of the placenta has long been recognised in the culture and detailed records of placental weight and size kept show that later hypertension was associated with reduced placental weight and surface area.
The fact that men suffer more often with hypertension than women may relate to the fact that male foetuses more readily sacrifice kidney function for brain development.
Foetal programming
Foetal programming is the term used to refer to the the process by which early malnutrition leads to lifelong changes in the body’s organs and systems, thereby initiating disease in later life. This reveals that human development is fragile and that insufficient resources during pregnancy lead to diminished supplies of stem cells and poorer immune defences which between them determine the future capacity for repair and renewal.
The research again shows that allopathic medicine - guided as it is by the interests of the pharmaceutical industry - has been completely overlooking the elephant in the room: nutrition. And that blaming of people for their conditions as being either lazy or greedy may have little foundation in fact.
Further resources
Click to view part 1 of the UK Horizon documentary entitled The Nine Months That Made You with remaining parts available under Fatigue Syndromes and Toxicity in the Video Hub or to go to David Barker's website for more information.
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