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Expectant mothers often asked us if their stress levels might influence the development of the baby’s  brain.

Maternal stress is known to influence the development of a child’s behaviour and ability to regulate his or her emotions as they grow. This is usually measured by questionnaires, which are very often unreliable.

In a recent study from Edinburgh researchers have used an objective measure -- levels of cortisol -- in the mother to study links with baby brain development.

Hair samples were taken from 78 pregnant women to determine the women’s levels of cortisol in the previous 3 months. Their babies underwent a series of brain scans using magnetic resonance imaging to examine the structure of the amygdala, and determine how it is connected to other parts of the brain.

The researchers found that there was a relationship between maternal hair cortisol concentration and amygdala development that differed according to infant sex. Higher hair cortisol concentration was associated with higher left amygdala fractional anisotropy, lower left amygdala orientation dispersion index, and higher fractional anisotropy in connections between the right amygdala and putamen in girls compared with boys. Furthermore, altered amygdala microstructure was only observed in boys, with connectivity changes restricted to girls.

So there may be differences in brain development caused by stress. A word of caution, however, this study did not assess emotion in children or the effect of these structural changes on behaviour.

“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,” concluded James Boardman, PhD, University of Edinburgh.