Is "baby brain" real?

A new study on brain changes during pregnancy & why we should stop being so hard on ourselves

[Image via The Blue Diamond Gallery]

If you’ve ever been pregnant (or spent time with pregnant people), you’ve probably talked about “baby brain.” Also known as “pregnancy brain,” “mommy brain,” or “pregnancy amnesia,” it’s the notion that your memory gets worse when you’re pregnant or after you have a baby. Pregnant friends have discussed completely forgetting what an everyday object is called (“Could you pass me the… uh… uh…” “The spoon?” “Yes, that word!”) or finding that they threw away their keys and put a banana peel in their purse. When I was pregnant I completely forgot about promising to make a baked good for friends until 11PM the night before our get together (side note: peanut butter blondies are a great last minute baking choice!)

It’s only recently that scientists have observed that our brains have the capability to change significantly after our first decade of life. Pregnancy seems to be one of those special times. Callaghan and colleagues (2022) recently published a study in Memory titled, “Evidence for cognitive plasticity during pregnancy via enhanced learning and memory” (Twitter thread from the lead author describing the study results here). They cite evidence on how our brains change during pregnancy, but mostly in adaptive ways. For example, pregnant rats show improvements in spatial learning and memory. This makes sense: a mother rat needs to remember her nesting location, the best places to forage/hunt, and how to keep track of her babies. The same logic probably applies to humans. Overall, the majority of studies don’t really show memory deficits during or after pregnancy in humans.

However, there are studies that show that pregnant women exhibit difficulties on verbal memory tasks. These tasks often involve someone reading you a bunch of words and then asking you to recall them later. Callaghan and colleagues, though, argue that these tasks aren’t great for assessing someone’s memory because they don’t use “ecologically relevant stimuli.” In other words, these tests ask people to remember random words that have no personal relevance for them. Instead of showing memory deficits, the fact that people can't remember a random list of words might just mean they didn't try very hard at the test.

So, these researchers decided to create a memory task, based on animal research, using stimuli that would be relevant for adult humans who are getting ready to become parents. They wanted to understand whether humans are more like rat moms, where our memory gets better during pregnancy, or whether there’s evidence supporting the idea that pregnancy causes “baby brain” and our memory gets worse.

They compared 74 pregnant women in their third trimester with 88 women who had never been pregnant on various memory tasks. The average age of women in the study was between 28-31 years old, representing a range of racial/ethnic backgrounds (for the pregnant women: 1% Asian American, 23% Black/African-American, 20% White, 55% other ethnicity not represented; across participants, 68% also identified as Hispanic).

Women went through a “Learning Phase” of viewing images of different objects and scenes paired together. Importantly, women were tested on images that were relevant for their lives, including baby-related (e.g., a high chair) and “adult-related” (e.g., office furniture) stimuli. Women were shown these images, with an object in front of a scene, in a specific location (e.g., a highchair on the left side of a scene of a lake), and were asked to imagine the object in the scene in as much detail as possible.

Women’s memories were tested in two different ways:

• Object-Recognition Test: Women were shown images of objects they saw during the Learning Phase along with objects that were similar, but they had never seen before. They were asked to state whether or not the object was old, new, or they didn’t know. This type of test is a pretty common and straightforward way to assess one’s memory for things (similar to recalling words from a list).

• Object-Scene Associative Memory Test: Women were shown a scene along with three objects. One of the objects was the one that had been paired with the same scene during the Learning Phase. First, participants were asked to state which object was paired with that scene during the Learning Phase. Next, they were asked where in the scene the object had been placed during the Learning Phase. This is more complicated than the Object-Recognition Test and kind of like trying to remember where the best food is (if you're a rat) or where you parked your new car (if you're a human). It involves not only remembering a specific object, but where the last “place” you saw that object (i.e., testing spatial learning).

These tests were each administered twice: immediately after the Learning Phase, and four weeks later.

Depiction of memory tests, from Callaghan et al. (2022)

Overall, the researchers found that pregnant women never performed worse than the never-pregnant women, regardless of type of object, type of memory test, or whether they were tested immediately after the Learning Phase or four weeks later. In fact, pregnant women sometimes performed better than never-pregnant women:

• Pregnant women recognized baby-related stimuli better than never-pregnant women on the object-recognition test, immediately following the Learning Phase.

• Pregnant women recognized both baby-related and adult-related stimuli better and were more accurate than never-pregnant women on the object-scene associative memory test, four weeks after the Learning Phase.

These results are in line with Team Rat Mom: Pregnant women appear to have enhanced long-term spatial associative memory (such as remembering that the last time they saw that specific bottle was to the right with the scene of a mountain). The researchers discuss the implications of this as it relates to the brain: Namely, that pregnancy may cause adaptive changes to the hippocampus (a brain structure often associated with this type of memory) versus other parts of the brain - though the researchers did not directly examine brain function in this study. This might explain why pregnant women did better on this task, while other studies show memory difficulties in pregnant women for things like remembering words from a list. Additionally, the authors found a slight advantage for pregnant women on baby-related stimuli on one (but not all) of the tasks, suggesting the importance of using ecologically valid stimuli to test memory.

This study suggests that, in many ways, our cognitive abilities just get stronger after pregnancy, not weaker.

They also bring up the role of mood symptoms on memory. In this study, pregnant participants had lower depression scores compared to the never-pregnant participants.

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It might be that any memory difficulties one might have during pregnancy are more related to symptoms like depression and anxiety, since those tend to be related to worse memory, than the experience of pregnancy itself. While depression symptoms were not related to memory performance in this study, the researchers discuss the importance of studying this more in the future.

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It can be pretty insulting how much emphasis there is on pregnant people, usually women, becoming “dumber” when they’re having a baby. It’s in the same ballpark as the “hormonal mother” trope. Sleep, mood, stress, how many things are on your plate on any given day… all of these things can affect memory. Parenting is a full-time job that takes a huge amount of coordination and mental effort. In heterosexual relationships, women take on the majority of household labor, and this gap has only gotten worse after the pandemic. Maybe give us a break if we put our keys in the trash a few times?!

I know women who successfully passed their qualifying exams on their way to getting a PhD while pregnant. Women who had to coordinate funeral plans from across the country while pregnant. Women who were taking care of multiple children while pregnant. Sure, I forgot to plan something one time. But I also started a tenure track faculty job during my second trimester, juggling a million new responsibilities at once.

It’s easy to be hard on ourselves when we’re not 100% competent at everything we do. Rather than hyper-focusing on (rare) moments of forgetfulness and foibles, we should instead be in awe of how, even in adulthood, our brains can change and adapt in new and amazing ways. As well as, ya know, work towards labor equity in all realms of life. If I’m going to forget a word here and there while my brain is preparing to handle all the other multi-tasking and new skills I need to develop to become a parent, I’ll take that trade-off. Instead of “baby brain” representing forgetfulness, it should represent the monumental mental fortitude that becoming a parent requires.

1. The researchers speculate that this was most likely because the never-pregnant participants’ data was collected during the pandemic, while data from pregnant women was collected before the pandemic.