Children who are deprived of a key hormone while they are in the womb are more vulnerable to anxiety in later life, a new study has suggested.
Scientists have found that levels of a hormone that controls the supply of nutrients from the mother plays a key role in how their offspring respond to anxiety in later life.
Low levels of the hormone, called Insulin-like growth factor 2, leaves the youngsters more prone to anxious behaviour and stress when they reach adulthood.
Losing weight and stress during pregnancy have both been found to lower the levels of this hormone in the past.
Now the scientists behind the latest study at Cardiff University and the University of Cambridge claim their findings may help to explain why some people respond badly to stressful and anxious situations compared to others.
Dr Trevor Humby, a behaviuoral geneticist and one of the co-authors of the study at Cardiff University, said: “This is the first example of what we have termed “placental-programming” of adult behaviour.
“We do not know exactly how these very early life events can cause long-range effects on our emotional predispositions, but we suspect that our research findings may indicate that the seeds of our behaviour and possibly vulnerability to brain and mental health disorders are sown much earlier than previously thought.”
The research, which is published in the journal of Nature Communications, looked at mice that lacked the ability to produce enough Insulin-like growth factor 2 while they were pregnant.
This hormone helps to control the growth of a fetus by ensuring it gets enough nutrients through the placenta from the mother.
The researchers found that mothers who produced too little of the hormone had an imbalance in the supply of nutrients and this then also affected how their offspring behaved in later life.
Mice that received too little of the hormone while in the womb became more anxious when performing maze tests or being placed in new environments once they were an adult.
Dr Hamby said that previous studies had shown that babies that suffer from restrictive growth while in the womb tended to be at a higher risk of emotional and behavioural disorders such as ADHD and anxiety, but none had drawn a direct link with the hormone before.
He said: “From our studies we believe that the inability of the placenta to provide adequate nutrition to the foetus, matching the demands of the foetus, leads to altered developmental trajectories of brain systems.
“During pregnancy the foetus is developing at quite a rate, and the brain is undergoing quite significant changes.
“Disruption of nutrient supply in terms of metabolites to provide energy for reactions but also as building blocks for the new substances being made, may lead to altered brain systems.
“This is what we aim to investigate next.”
It comes after separate research showed that unborn babies exposed to the stress experienced by their mother are also at a higher risk of anxiety and depression .
This occurs when a natural defence mechanism in the placenta stops working and the unborn baby is exposed to the stress hormones, causing the way their brain develops to change.
Professor Lawrence Wilkinson, a behavioural neuroscientist at Cardiff University who led the latest research on the growth hormones, added: “The growth of a baby is a very complex process and there are lots of control mechanisms which make sure that the nutrients required by the baby to grow can be supplied by the mother.”
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