The 'Barker hypothesis' explains that our organs and their functions undergo 'programming' during our time as an embryo and foetus. This programming then determines to an extent how these organs and functions will behave into childhood and adulthood.
Certain environmental factors can result in the fetus developing adaptations, say, to deal with maternal malnutrition or undernutrition. These adaptations can lead to permanent structural, physiological and metabolic changes which can predispose the fetus to cardiovascular, metabolic and endocrine disease in later life.
Animal studies have shown that the body has a 'memory' for undernutrition in utero. This can alter blood pressure, cholesterol metabolism, insulin response to glucose, and other metabolic, endocrine and immune functions important to human diseases.
The fetus is affected by the maternal status - her diet, body composition, blood flow to the uterus and placenta, and genes. A severe restriction in maternal nutrition will cause changes in the production of fetal and placental hormones that regulate metabolism, blood flow and control growth. Prolonged undernourishment causes a reduction in metabolic rate - and this is why we see low weight babies being predisposed to obesity and diabetes later in life.
If there is a severe undernourishment in late pregnancy when organs and tissues are growing rapidly, the fetus will have to prioritise growth - and this goes mostly to the brain tissue - which is essential for immediate survival. This leads to blood flow being directed away from the liver and abdominal tissues, leading to slowed growth in these areas.
Luckily, in the western world, we have many resources available to us so we do not see many cases of severe maternal undernourishment. We have high quality supplements available to us, and we have the access to good food which can nourish us and our baby.
The reason we have highlighted Fetal programming is to show you just how vulnerable the fetus is to maternal influence. With the rise of diabetes, obesity and ill health starting in childhood, we really do need to be aware of just how delicate our babies are in utero.
Yes, our bodies are designed to grow a human from start to finish in even the most dire of circumstances - but this would be at a cost. It is our job to make sure that we are receiving the right nourishment from our food to create the healthiest baby we can.
A little explanation of some of the words used above!