The changes, thought to have evolved to help a mother focus fully on the needs of her baby, cause some parts of the brain to shrink as neural networks become more specialised.
This lasts for “up to two years after giving birth”, researchers at Universitat Autonoma de Barcelona (UAB) in Spain found. However, there was no evidence of any impairment to memory or other mental functions.
“The findings point to an adaptive process related to the benefits of better detecting the needs of the child, such as identifying the newborn’s emotional state,” said co-author Dr Oscar Vilarroya, from UAB, according to PA.
Twenty five first-time mothers were studied using magnetic resonance imaging (MRI) brain scans.
The scientists found that during pregnancy the volume of grey matter making up the cell bodies of neurons reduced in specific areas of the “cerebral cortex”, the part of the brain involved in higher functions.
The same effect was not seen in 20 women who had never been pregnant, or participants’ male partners. From the extent of the brain changes, the scientists were able to predict how attached a mother was to her baby after giving birth.
Researchers found the process mirrored the “synaptic pruning” that occurs in teenagers as their brains mature.
The researchers wrote in the journal ‘Nature Neuroscience’: “On the basis of our results, we may speculate that the female brain undergoes a further maturation or specialisation of the neural network during pregnancy.
“Very few studies have investigated the effects of pregnancy on measures of social cognition, but there are preliminary indications of facilitated processing of social information in pregnant women, including enhanced emotion and face recognition.”