Is it true that cognitive abilities decline during pregnancy?

It is a common belief that while expecting a child, women remember information worse, think slower and become more absent-minded. We decided to check whether this stereotype is supported by scientific data.

To describe the mental capabilities of expectant mothers, many names are used - ranging from ironic to more rude: "mamnesia", "motherhood of the brain", "full pregnant", “the child literally eats the mother’s neurons”. On specialized forums you can find dozens of stories of women who complain about absent-mindedness, forgetfulness, decrease attention, impossibility concentrate And decide work tasks are as easy as before pregnancy. There is also information in the media that the volume of gray matter in the brain of pregnant women decreases. In particular, they write about this "Gazeta.ru", "Rossiyskaya Gazeta" And RIA Novosti.

The study on changes in the volume of gray matter in the brain of pregnant women, which the media refers to, is really exists. However, not all journalists correctly conveyed its essence in all publications.

In 2016, the authoritative medical journal Nature Neuroscience published an article “Pregnancy causes long-lasting changes in the structure of the human brain.” Scientists from Spain and the Netherlands relied on a sample of just 25 pregnant women who had MRI scans of their brains while they were pregnant and for the next two years if they did not become pregnant again. The brain structure of these 25 women expecting to become mothers was compared with the brain structure of 19 men expecting a new addition to their family, as well as with a control group of 17 childless men and 20 women not planning to become pregnant.

In pregnant women, changes were seen in areas involved in social interaction and recognizing emotions from facial expressions, as well as hippocampus - a paired structure of the temporal regions, responsible for the transition of short-term memory to long-term memory, participating in the work of spatial memory necessary for orientation and navigation, and in the mechanisms of formation of emotions. However, the researchers clarified that, despite the quantitative decrease in gray matter, they did not note any significant qualitative deterioration. Pregnant women demonstrated the same memory abilities as the control group (with some exceptions for verbal memory, that is, remembering information read or heard, but the level of difference was not sufficient for a statistically significant result).

Researchers have suggested that the reason may be synaptic pruning — reducing the number of neurons to increase the overall efficiency of the neural network (we also experience this in early childhood and adolescence). In other words, the brain gets rid of the least valuable elements, transferring their functions to neighboring ones in order to optimize its resources. Synaptic pruning can be compared to taking inventory - the brain determines what it really needs and what can be “recycled” and use the freed up space in a more useful way.

By calculations others scientists, during pregnancy, brain volume can decrease by 6–7%. At the same time, experiments showed the reversibility of such changes. In particular, observations Dr. Pilyan Kim from the University of Denver demonstrated an increase in gray matter volumes three to four months after childbirth. Most new neurons were formed in the hypothalamus, substantia nigra, amygdala, parietal lobe and prefrontal cortex. These areas answer for processing sensory information, emotions and pleasure, as well as motivation.

Pregnancy provides other benefits to the brain. So, in 2009 scientists from the University of Bristol found that women in late pregnancy are better able to recognize negative emotions (anger, rage, disgust and sadness) from faces, and in 2011, Canadian researchers noticedthat pregnant women remember faces better after a single interaction.

No less interesting results are shown by experiments over animals. Thus, it was noticed that mother rats are more successful than their nulliparous rivals in situations of versatile activity. In the process of searching for a treat, the animals had to simultaneously monitor visual, sound and olfactory signals and, at the same time, monitor the behavior of their rivals. In 60% of cases, rats that carried two or more pregnancies won; in 33% of cases, females who had given birth once took the lead, and only in 7% did nulliparous animals manage to be the first to find a treat. 

At the same time experiments over animals also included those species that are characterized by the active participation of males in the process of education. In a Brazilian experiment, male marmoset monkeys, who are characterized by the active involvement of their partner in the process of caring for newborns, showed better results in maze navigation and food search competitions if they had already had experience of fatherhood. Similarly, fathered Californian hamsters outperformed their childless rivals.

Where does the stereotype of “brain mothering” come from? Scientists suggest that its causes should be sought not in physiology, but in psychology. In 2014 study American psychologists showed that pregnant women and those who have just given birth cope with a set of tests on verbal and spatial memory, attention, language skills and the ability to plan and self-control as well as non-pregnant women from the control group, while they themselves rate their results unreasonably worse. Their own assessment of their skills was underestimated even after they were given the test results. “I was amazed to see how ingrained in them was the idea that their results weren’t good enough,” speaks Michael Larson from the research group.

Thus, although scientists have identified a quantitative decrease in brain volume during pregnancy, they have not been able to reliably link it with a qualitative deterioration in cognitive abilities. Moreover, numerous experiments show that memory, attention and the ability for analytical thinking often decrease only in the subjective perception of the woman herself, but in fact, the “pregnant” brain copes with these tasks no worse than before.

Mostly not true

What do our verdicts mean?

Read on the topic:

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