Quoted in an article for The Atlantic, artist Sarah Walker describes becoming a mother like “discovering the existence of a strange new room in the house where you already live.”  It’s a profound statement that captures what most new moms feel: a strange, unfamiliar feeling within us, particularly in the first year.

That unfamiliar feeling isn’t entirely surprising. The transition to motherhood—termed matrescence—changes … everything. Research is clear about the social, relational, financial, emotional, and occupational shifts that come with motherhood.

But what’s not been talked about much is how pregnancy and postpartum literally change our brain.

Numerous studies on other mammals indicate significant changes in the brain during this vulnerable time. But that research hasn’t been explored in human mothers until more recently. 

And what researchers are now finding is fascinating: We may not feel like ourself post-baby because we’re not ourself. At least not our same pre-baby self! 

It turns out that in pregnancy and postpartum, our brain actively changes and adapts—more than any other point in our lives—to meet the new challenges of motherhood head-on.

Neuroplasticity 101

Bear with me here, because I need to get a bit sciency… 

Our brain is made of billions of nerve cells. The spaces between these cells are called synapses. The firing of neurotransmitters—chemicals that facilitate nerve impulses jumping from one synapse to another--forms the basis on which our brains function. 

Neuroplasticity is the brain’s ability to form and reorganize these synaptic connections throughout our lives. When we’re young, our brain has the highest plasticity; it’s able to take in mountains of information and change accordingly.

These changes continue as we age as we take in new information and experiences, but neuroplasticity is especially important in puberty, as increased hormones cause structural changes to our brains. Then, in pregnancy and postpartum, even more structural changes occur. Which makes sense, considering the surge of hormones we get from the placenta.

These structural changes may also be related to synaptic pruning. Synaptic pruning is the process of the brain essentially cutting off function to various areas in the brain it no longer needs, so that it can specialize in areas that are more crucial. This process facilitates new connections, helping us focus on new skills. Like, for example, learning to take care of an infant.

While neuroplasticity and synaptic pruning can happen all over the brain, researchers have noticed several key areas where things seem to change a bit more than expected. And these areas have massive implications for how we change during the pregnancy and postpartum period.

The Amygdala

The amygdala is an almond-shaped set of neurons in the lower center of the brain. It helps process memory and drives primal emotional reactions like fear and aggression. In pregnancy and postpartum, researchers have found clinically significant growth in this area of the brain.

Most of the growth in the amygdala is hormonally charged. This region of the brain is highly susceptible to oxytocin, which surges in pregnancy and postpartum. 

From an evolutionary perspective, oxytocin helps us bond with our offspring. And growth in this area of the brain—caused by that increase in oxytocin—helps us to deepen that connection. It makes us hypersensitive to our baby’s needs and creates a positive feedback loop that continuously motivates our behaviors.

For example, when you hear your little one coo, your brain releases oxytocin. This causes you to go to your child, smile, and coo back, effectively bonding with them. This releases more oxytocin, causing you to want to do those things when they happen again. The growth in the amygdala makes you even more sensitive to this process, promoting more bonding and attentiveness to your baby.

The Prefrontal Cortex

The prefrontal cortex is the brain matter behind the forehead and along the top of the head. It’s the largest portion of our brain, primarily responsible for executive functioning—all the mental processes that help us to plan, focus attention, and juggle multiple tasks at once.

In postpartum women, researchers have found an increase in gray matter volume. Our prefrontal cortexes have essentially gotten bigger! This suggests our brain is adapting to motherhood in an entirely different way. Rather than focusing on bonding and attentiveness, growth in the prefrontal cortex serves to help us manage all the competing tasks of taking care of a newborn.

For example, pre-baby, you probably didn’t imagine soothing a screaming infant while heating a bottle while talking with your toddler all on very little sleep. But, thanks to growth in the prefrontal cortex, you’ve become a veritable superhero.

The Hippocampus

Ever felt “mommy brain”? It’s that combination of forgetful, foggy, and scatterbrained we often get as moms. One study found that as many as 80% of us experience this at one time or another. 

While mom brain might be caused by short-term factors like fluctuating hormones, sleep deprivation, and elevated stress, it could also be due to structural changes in our brain. 

The hippocampus is a complex brain structure lodged deep in the midbrain. It plays a huge role in things like learning and memory. And, during pregnancy and early postpartum, it shrinks. Research shows this causes specific issues with verbal recall and working memory.

Words on the tip of your tongue? Can’t remember why you walked in the room? Keep calling your kids by the wrong names? 

It’s all the hippocampus.

What’s Next?

Researchers aren’t quite sure how long these changes last. One study found structural changes two years after birth. Studies on other mammals indicate our brain may stay this way forever, lending to the phrase, “Once a mother, always a mother.”

Researchers also aren’t certain about the impact these structural changes in the brain have on mental health concerns like postpartum depression or anxiety. But what we do know is this is a very vulnerable time for our brains. Perhaps the most vulnerable time.

So, give yourself grace. Motherhood has changed everything, including your brain. Be kind to yourself as you handle this transition. You deserve it.

Matrescence can be hard.

That’s why I created Keeping Mommy in Mind, an online course to help you navigate the transition to motherhood with confidence and joy. Check it out!

Sources

Barba-Müller, E., Craddock, S., Carmona, S., & Hoekzema, E. (2018). Brain plasticity in pregnancy and the postpartum period: Links to maternal caregiving and mental health. Archives of Women's Mental Health, 22(2), 289–299. https://doi.org/10.1007/s00737-018-0889-z 

Duarte-Guterman, P., Leuner, B., & Galea, L. A. M. (2019, February 28). The long and short term effects of motherhood on the brain. Frontiers in Neuroendocrinology. Retrieved from https://www.sciencedirect.com/science/article/abs/pii/S0091302218301237?casa_token=tPrkU3P7MIgAAAAA%3A9_2_1C-AbZ8AWsAsx34ZWZ2k8Rm-AToQ5l847wFDbCe1GsZlh3uRygqIgmsemhy54KUQ3v0bvA 

Gritters, J. (2020, May 5). This is your brain on motherhood. The New York Times. Retrieved from https://www.nytimes.com/2020/05/05/parenting/mommy-brain-science.html 

Kim, P., Leckman, J. F., Mayes, L. C., Feldman, R., Wang, X., & Swain, J. E. (2015). The plasticity of human maternal brain: Longitudinal changes in brain anatomy during the early postpartum period. Behavioral Neuroscience, 124(5), 695–700. https://doi.org/10.1037/a0020884 

LaFrance, A. (2021, July 16). What happens to a woman's brain when she becomes a mother. The Atlantic. Retrieved from https://www.theatlantic.com/health/archive/2015/01/what-happens-to-a-womans-brain-when-she-becomes-a-mother/384179/ 

Wadman, M. (2016, December 19). Pregnancy resculpts women's brains for at least 2 years. Science. Retrieved from https://www.science.org/content/article/pregnancy-resculpts-women-s-brains-least-2-years