What Happens to Your Brain When You Have a Baby, According to a Psychologist

You keep losing your train of thought mid-sentence…and your car keys. Yep, we’ve all heard of mom brain—and if you’re a new or expecting mother, there’s a good chance you’re living with it right now. But is mom brain a real thing or is it just a big, weird coincidence that so many other birthing people are in the same boat (and feeling, well, lost at sea)? We consulted clinical psychologist Dr. Bethany Cook to get to the bottom of what happens to your brain when you have a baby, and here’s what we learned. Spoiler: That foggy feeling isn’t just in your head. (Pun intended.)

In case you need a neuroscience refresher, gray matter is the pinkish-gray stuff that makes up the outermost layer of the brain, and it owes its color to a high concentration of neuronal cell bodies; it also plays a critical role in executive functioning, motor control, emotional regulation, social cognition and every other form of information processing you can think of. (Psst: You’d have a very hard time reading this article and thinking about these things without the gray matter in your brain.) 

Interestingly enough, the latest research—specifically this pioneering 2016 study conducted by Dr. Elseline Hoekzema and published in Nature Neuroscience—has shown dramatic changes occur in the brains of pregnant women and new mothers, and one such change is a decrease in the volume of gray matter. This might sound like bad news, but don’t worry, mama—it doesn’t actually mean you’ve gotten stupider (or at least not for nothing). Per Dr. Cook, “the theory behind gray matter shrinking is that a new mothers' brain becomes more efficiently wired and able to care for and teach her helpless tiny human.” In other words, the reduction in gray matter is a beneficial, adaptive change that ensures mothers can allocate their resources appropriately (i.e., devote their brain power to caretaking).

Neural pruning is the body's natural process of removing neurons that are no longer useful to the brain—and a lot of pruning goes on during and after pregnancy. In fact, it goes hand-in-hand with the reduction of gray matter we just talked about and is the means by which the brain makes itself “leaner and more resourceful, whilst allowing for new pathways to be created with the additional needs of the baby in mind,” says Dr. Cook.

Given what you now know about post-baby changes to gray matter and neural pruning in the brain, it should come as no surprise that this correlates with a loss of mental space. (Hint: That’s why you might feel simultaneously spaced out and like you’re operating in overdrive.)

“Psychologically speaking, a woman's brain post baby turns into a computer that never stops running, tracking and calculating their infants every move and sound from sleep to food to poop,” says Dr. Cook. Indeed, “There is so much ‘new’ that a mother’s mind can never shut down or go on standby. Add a changing body, hormone roller coasters, leaky boobs and painful toilet breaks to the mix and you’ve got yourself an overtaxed mind.” Bottom line: Reduced gray matter and rapid neural pruning are fancy research-backed changes that occur in the brains of new moms, while a loss of mental space (i.e., that overwhelmed and foggy feeling) is the consequence you’re experiencing on the daily.

As previously mentioned, your brain as a new mom is shrinking for a very good reason. Still, the thought of losing gray matter isn’t exactly uplifting, so let’s lighten the mood. According to Dr. Cook, “Studies have shown growth in the prefrontal cortex of the brain of new mothers, which is the area responsible for learning, planning, delayed gratification and judgment. They also found growth in the parietal lobes (i.e., the brain's emotional regulation center), and the temporal lobes, which are associated with empathy and understanding.”

Basically, your executive functioning and memory might have taken a temporary hit, but you’re getting better in other ways—namely because this growth “improves mom’s ability to learn how to read and understand non-verbal cues, allows for deeper connections and attachment, and gives mom the extra patience needed to care for an infant as well as herself.” That’s right, there’s actual science behind maternal instinct.

Here, another area of growth. Research has shown that a woman's amygdala—the part of the brain involved in processing threatening stimuli and activating the body's response to dangerous stimuli—increases after having a baby. “This enlarged amygdala makes a mother more hypersensitive and responsive to the needs of her new baby and her surroundings in an effort to keep everyone safe,” says Dr. Cook, adding that “it’s also involved in creating and maintaining a positive feedback loop between mother and infant behaviors.”

You just had a baby and suddenly you’re experiencing Eternal Sunshine of the Spotless Mind IRL. Memory lapses and fogginess are almost ubiquitous among new moms, and there are numerous factors—the one-two punch of an increased mental load and decreased sleep, for example—that contribute to this dazed and confused feeling. However, some researchers say the aforementioned structural changes to the brain have an impact on memory—and yes, this also serves an evolutionary purpose. “It's been postulated that evolution has made women ‘forget’ the pains and trials of childbirth and the early years as a way to ensure they continue to procreate. The takeaway? If your memory has been failing you as of late, it’s probably because a) you’re busy coping with all the moving parts of motherhood and b) nature decided to do you a solid.

Mommy brain is more than just a cute way of laughing off the serious lack of sleep you’re suffering from; it’s a science-backed phenomenon. That said, nothing has really been lost—areas of the brain have simply become more refined and specialized, so that motherhood can become one of your areas of expertise. Nevertheless, the struggle is real, which is why you might take comfort in knowing that the changes described above are not believed to be permanent (they’re thought to last for roughly two years, possibly longer) and all of them facilitate that heart-swelling and oh-so important attachment you share with your babe.