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The term “mommy brain” is commonly used by pregnant mothers to describe their scattered and foggy mental state during pregnancy. Some would even say it is a rite of passage as an expecting mother. While there is no official diagnosis for this, symptoms of disorientation, memory loss, trouble concentrating and other cognitive challenges can make daily tasks seemingly more difficult.

Despite an entire term being dedicated to this common state of the maternal brain, it is astonishing that the exact cognitive changes happening during gestation are still virtually unknown. While pregnancy is such a common occurrence, the research surrounding what exactly happens to the brain during pregnancy is almost nonexistent. The evidence that researchers have worked to gather about the maternal brain has been either before or after pregnancy, as opposed to during.

“Despite an entire term being dedicated to this common state of the maternal brain, it is astonishing that the exact cognitive changes happening during gestation are still virtually unknown.”

Each year, around 140 million women become pregnant worldwide. Over the course of pregnancy (an approximately 40 weeklong period), the mother’s body undergoes significant physiological changes, affecting cardiovascular health, metabolic rate, immunity, oxygen consumption, and more, all in response to the development of the fetus. The quick onset of these physiological changes is triggered by an increase in hormone production by a factor of 100 to 1000. This surge of hormones includes increased estrogen, progesterone, and other neuromodulators which lead to considerable reorganization of the central nervous system (CNS). Due to the high increase of hormones experienced during pregnancy, it is clear that the brain is highly affected amongst the other profound changes occurring in various organ systems.

While the lack of understanding as to what occurs in the expecting mother’s brain has been lacking for millions of births, one woman was presented the unique opportunity to fully study the brain throughout the entirety of her pregnancy. Neuroscientist, Liz Chrastil, knew that she wanted to start a family with her husband, so she took on the opportunity of studying her own brain throughout the entire process. A new study published in Nature Neuroscience, presents new evidence as to how the brain develops throughout the time preceding and following birth, by following the pregnancy journey of Liz Chrastil.

From preconception to gestation to postpartum, this study was able to document the evolving brain through every stage in a healthy 38-year-old woman’s pregnancy. While Chrastil was the only participant in the study, she was not alone in documenting the process. A team of collaborators, who also have a background in studying what occurs in the brain throughout the menstrual cycle and menopause, oversaw the study of Chrastil’s pregnancy and how it affects her brain. From 3 weeks preconception through 2 years postpartum, the team conducted 26 MRI scans and blood draws.

“From preconception to gestation to postpartum, this study was able to document the evolving brain through every stage in a healthy 38-year-old woman’s pregnancy.”

Since the brain during preconception and postpartum have historically shown differences when being compared, scientists have been able to gather compelling evidence that there are neurological shifts happening during gestation. Outstanding questions remained such as the timeline of these anatomical changes occurring and whether they were in relation to the significant increase in hormone production. This new study was able to offer answers to these previously unknown questions by providing neuroscientist with a specific timeline of a mother’s brain throughout gestation. The findings of this study aligned with the prior understanding that pregnancy is an unbelievable period of neuroplasticity, highlighting the brain’s outstanding ability to be so adaptable through this surge of hormonal changes beyond adolescence.

Results from this study demonstrated specific structural changes which are critical in the brain for triggering maternal behavior, displayed the strongest changes over the gestation period. They saw a reduction in gray matter volume (GMV) that was long lasting and remained the two years following Liz Chrastil’s son’s birth. As a result of the decrease of GMV, neuromodulatory hormones begin to remodel themselves in preparation for motherhood. Previous evidence has shown that reductions of GMV corresponds with increasing levels of parental attachment.

“Results from this study demonstrated specific structural changes which are critical in the brain for triggering maternal behavior.”

They also found that the white matter, responsible for connecting and communication amongst different brain regions, was strengthened during the first and second trimester, but reverted back following the birth. This reversion back to baseline is not to be considered so much a loss, but more so seen as a refinement. With the rise in hormones, a variety of physiological changes may occur in parallel. Some of these changes could affect body mass index (BMI), water retention, sleep quality, and more, highlighting the importance of mapping the brain’s specific response and reorganization as a result of the increase in hormones.

The dynamic neurological shifts which occur during the entire process of pregnancy are essential to the understanding of a mother’s behavior, risk of developing mental health conditions, and aging in the brain. Studying the brain throughout gestation helps to reveal specific alterations of neural circuits that help prepare for motherhood. This study demonstrates the neuroplasticity that occurs throughout pregnancy and just how dynamic of an organ the brain truly is. In just a 40-week period, the brain can drastically shift for an expecting mother, marking pregnancy as one of the highest periods of neuroplasticity experienced in adulthood.

Note from the Editors:

We had previously reviewed the topic of pregnancy effects on the mother’s brain, but thought it was interesting enough to deserve another review. In the following we are also including a list of recent scientific publications on the same topic.

The plasticity of human maternal brain: longitudinal changes in brain anatomy during the early postpartum period
P Kim et al. Behav Neurosci JAN. 1, 2010
Animal studies suggest that structural changes occur in the maternal brain during the early postpartum period in regions such as the hypothalamus, amygdala, parietal lobe …

The long and short term effects of motherhood on the brain
P Duarte-Guterman et al. Front Neuroendocrinol JAN. 1, 2019
Becoming a mother is associated with dramatic changes in physiology, endocrinology, immune function, and behaviour that begins during pregnancy and persists into the post …

Cognitive impairment during pregnancy: a meta-analysis
SJ Davies et al Med J Aust JAN. 15, 2018
General cognitive functioning, memory, and executive functioning were significantly poorer in pregnant than in control women, particularly during the third trimester.

The maternal ‘baby brain’ revisited
CK Barha et al Nat Neurosci JAN. 27, 2017

The effect of pregnancy on maternal cognition
G Barda et al. Sci Rep JUNE 9, 2021
To determine whether there are differences in measures of cognitive function between second and third trimester pregnant women compared to non-pregnant controls.

Pregnancy leads to long-lasting changes in human brain structure
E Hoekzema et al. Nat Neurosci JAN. 1, 2017
Pregnancy involves radical hormone surges and biological adaptations. However, the effects of pregnancy on the human brain are virtually unknown.

Father’s brain is sensitive to childcare experiences
E Abraham et al. Proc Natl Acad Sci USA JULY 8, 2014
Although contemporary socio-cultural changes dramatically increased fathers’ involvement in childrearing, little is known about the brain basis of human fatherhood