Stress during pregnancy 'can affect baby's brain development'

Stress during pregnancy can affect how a baby’s brain develops and lead to emotional problems in later life, study finds

  • Experts find link between a mother’s stress and structure of their baby’s brain
  • Higher stress hormone in mothers resulted in structural changes in amygdala
  • This brain region is involved in emotional and social development in childhood
  • Scientists call for more support for mothers to combat stress during pregnancy 

Stress during pregnancy can affect how a baby’s brain develops and may even lead to emotional problems when it grows up, a new study claims.  

UK researchers linked higher levels of the stress hormone cortisol in mothers with structural changes in the amygdala – the small almond-shaped cluster of neurons located in each side of the brain – of newly born babies.  

Cortisol is involved in the body’s response to stress – with higher levels indicating higher stress – and also plays a role in foetal growth. 

While the amygdala – of which there are two in each hemisphere of the brain – is known to be involved in emotional and social development in childhood. 

The study authors call for extra support for pregnant women to prevent any structural abnormalities in the amygdala. 

Baby brains may be shaped by levels of stress their mother experiences during pregnancy, a brain scanning study at the University of Edinburgh has revealed

‘Our findings are a call to action to detect and support pregnant women who need extra help during pregnancy as this could be an effective way of promoting healthy brain development in their babies,’ said Professor James Boardman at the University of Edinburgh. 

The experts add that pregnant women who feel stressed or unwell should seek help from their midwife or consultant and that with support, most health issues can be well managed in pregnancy.


The amygdala is an almond-shaped structure in the brain.

Humans have two amygdala – one in each temporal lobe of the brain.

Amygdalae are each formed of a cluster of nuclei – a collection of neurons, or nerve cells. 

Each amygdala is located close to the hippocampus, in the frontal portion of the temporal lobe.

Amygdala is the integrative centre for emotions, emotional behaviour, and motivation. 

Amygdalae are essential to the ability to feel certain emotions and to perceive them in other people. 

Maternal stress is known to influence the development of the child’s behaviour and ability to regulate its emotions as it grows, but this is usually measured by questionnaires, which are not always reliable.

Researchers therefore used an objective measure – levels of the hormone cortisol – in the mother to study links with baby brain development.

For the study, scientists took hair samples from 78 pregnant women to determine the women’s levels of cortisol in the previous three months.

The women’s babies underwent a series of brain scans using magnetic resonance imaging (MRI) – a non-invasive scan that took place whilst the baby slept.

The researchers found that higher levels of cortisol in the mother’s hair were linked to structural changes in the infants’ amygdala as well as differences in brain connections.     

Structural changes refers not to the overall size of the amygdala, but rather to its cellular architecture – the structure and form of the its neurons (also known as nerve cells).  

Researchers also observed changes in the strength of connections of pathways that connect the amygala with other brain regions that are important for emotion processing. 

Interestingly, being exposed to higher cortisol levels in the womb affected babies in different ways based on their sex.

Boys showed alterations in the fine structure of their amygdala, while girls displayed changes in the way the region connected to other neural networks. 

The study could explain why children whose mothers experienced high levels of stress during pregnancy may be more likely to have emotional issues in later life. 

The amygdala, shown here in red, is is the centre for emotions, emotional behaviour, and motivation. Humans have two amygdala – one in each temporal lobe of the brain

The researchers caution, however, that the study did not assess emotion in children.  

‘This research highlights how important it is to support women’s mental health during pregnancy to ensure their needs are met and their babies have the best start in life,’ said Sarah Brown at children’s charity Theirworld, which funded the study.

‘Helping mothers cope with stress is an important step to ensure both mum and baby thrive.’ 

Stress during pregnancy, for example because of mental or physical disorders, is already known to have long-term effects on child development. 

Epidemiological studies have shown that individuals exposed to stress in the womb are at higher risk of developmental and mood conditions, such as ADHD and depression. 

The study has been published in the journal eLife. 


A neuron, also known as nerve cell, is an electrically excitable cell that takes up, processes and transmits information through electrical and chemical signals. It is one of the basic elements of the nervous system.

In order that a human being can react to his environment, neurons transport stimuli.

The stimulation, for example the burning of the finger at a candle flame, is transported by the ascending neurons to the central nervous system and in return, the descending neurons stimulate the arm in order to remove the finger from the candle. 

A typical neuron is divided into three parts: the cell body, the dendrites and the axon. The cell body, the centre of the neuron, extends its processes called the axon and the dendrites to other cells.Dendrites typically branch profusely, getting thinner with each branching. The axon is thin but can reach enormous distances. 

To make a comparable scale, the diameter of a neuron is about the tenth size of the diameter of a human hair. 

All neurons are electrically excitable. The electrical impulse mostly arrives on the dendrites, gets processed into the cell body to then move along the axon.

On its all length an axon functions merely as an electric cable, simply transmitting the signal. 

Once the electrical reaches the end of the axon, at the synapses, things get a little more complex. 

The key to neural function is the synaptic signalling process, which is partly electrical and partly chemical. 

Once the electrical signal reaches the synapse, a special molecule called neurotransmitter is released by the neuron.

This neurotransmitter will then stimulate the second neuron, triggering a new wave of electrical impulse, repeating the mechanism described above.

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