Researchers have revealed that infants’ brains may be shaped by levels of stress their mothers experience during pregnancy.

The study, published in the journal eLife, suggests that stress levels in mothers – measured by a hormone linked to anxiety and other health problems – is related to changes in areas of the infant brain associated with emotional development.

“The findings highlight the urgent need for women to be better supported with their mental and physical health before and during pregnancy, and could help them spot mums and babies who need help,” said study authors from the University of Edinburgh in the UK.

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.

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

The new study is the first time that scientists have used an objective measure – levels of the hormone cortisol – in the mother to study links with baby brain development.

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

The research team showed that levels of cortisol are linked to the development of the baby’s amygdala, an area of the brain known to be involved in emotional and social development in childhood.

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, or 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.

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

“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 study author James Boardman.