New Study Looks at How the Brain Changes During Pregnancy and It’s Incredible

The brain undergoes several changes. Here's what experts have to say.

Fact checked by Sarah ScottFact checked by Sarah Scott

As a mom of five kids, sometimes I felt like my mind didn't feel the same with each pregnancy. Now, a new study out of UC Santa Barbara, and published in the journal Nature Neuroscience, confirms I may be onto something.

Researchers looked at the brain of a healthy 38-year-old, first-time mom-to-be over the course of her pregnancy, as well as two years postpartum. They took 26 MRI scans and blood tests. They compared what they saw with eight people who were not expecting.

They found the brain undergoes several changes during pregnancy and here's what it may mean.

The Brain During Pregnancy

In the new study, co-author Laura Pritschet, a PhD student, and her team determined that along with a rise in estrogen and progesterone, the gray matter in the pregnant woman’s brain deteriorated over the course of her gestation, starting as early as the ninth week.

Gray matter, also known as the cerebral cortex, makes up about 40% of the brain and is essential for controlling movement, memory, and emotions.

The authors also noted cortical thinning, which occurs naturally as we age, as well as enhanced white matter. White matter makes up about 60% of the brain and helps with processing information.

Some of the changes, including the reduction in gray matter, remained two years postpartum, while others, such as the white matter increase, were temporary.

Past studies have also examined changes in the brain during pregnancy, including the decreases in gray matter volume, as well as a reduction in brain size.

What Brain Changes During Pregnancy Could Mean

Of course, this may not be the case for every pregnant person's brain and more research needs to be done. But the brain changes observed in the study shouldn’t be looked at in a negative light, according to Sanam Hafeez, PsyD, a New York City-based neuropsychologist, and Director of Comprehend the Mind.

“Such mutations might help the brain cope with new motherhood, readying women to spend time with their newborn babies and cope with childbirth's stress and cognitive strain," says Dr. Hafeez.

She adds, “Although some cognitive functions such as memory can look temporarily changed, the underlying neural rewiring appears to favor social and emotional changes in this crucial period of development.”

Delia McCabe, PhD, a neuroscientist and author of the Lighter, Brighter You! blog, seconds the notion that essentially, brains are altered during pregnancy because they have to. These “changes make intuitive sense because the brain does have to change to ensure the next generation has the best chance of thriving," adds Dr. McCabe.

Meanwhile, the gray matter in a pregnant person’s brain decreasing as the white matter increases is associated with “fine tuning” the brain, and improving neural efficiency, specifically around social cognition, points out Amy Reichelt, PhD, a nutritional neuroscientist.

“Studies with animals have shown that the hippocampus—crucial for memory and spatial navigation—experiences changes that may aid in the cognitive demands of caring for a newborn," she says. "Additionally, the functional connectivity between various brain networks is modified, suggesting a widespread rewiring to support the transition to motherhood."

What About the ‘Mom Brain’ Phenomenon?

Putting milk in our pantry. Referring to the oven as the dishwasher. Driving the wrong route to pick up my daughter from practice. These are just a few examples of things I’ve done over the years that I wrote off as being the result of so-called “mom brain” or “pregnancy brain.”

Do the changes to the brain that happen during and after pregnancy explain these misty moments of cognition? The good news, as Dr. Hafeez stresses, “Rather than evidence of some kind of brain degeneration, the study suggests that significant brain adaptation takes place in pregnancy and that these adaptations are not harmful and might even be healthy.”

Dr. Reichelt agrees, emphasizing, “The observed brain changes in this study appear to be adaptive, preparing women for the demands of motherhood rather than causing harm.”

As for my milk carton misplacement? Dr. McCabe says an instance of forgetfulness may be explained by the “restructuring” of the brain during pregnancy, which results in our cerebrums focusing on other things, such as raising little people.

Dr. Reichelt validates that while “mom brain” moments are anecdotally common, research indicates that brain fog people experience during pregnancy and after isn’t the result of any “damage” in the brain.

Instead, she says, “These cognitive shifts are often temporary and may be more closely related to changes in hormone levels, sleep deprivation, and new responsibilities that come with caring for an infant.”

Brain Changes and the Postpartum Period

Along with the cognitive functional changes taking place during pregnancy, are hormonal and emotional shifts. And for many people, postpartum depression and anxiety take root after birth, which, as Dr. Hafeez tells Parents, may be explained by what’s going on in the brain.

“One group of brain regions that seem to be important are those that are involved in emotional regulation, stress responses, and social cognition,” she says.

Dr. Hafeez goes on to elaborate, “Brain remodeling changes during pregnancy affect the amygdala, hippocampus, and prefrontal cortex—areas involved in emotion processing and stress response. Hormonal changes associated with pregnancy—especially shifts in estrogen, progesterone, and oxytocin—can also affect these areas and can alter mood regulation.”

So, what does that mean exactly?

“Any time hormones are involved in brain changes—which is the case in pregnancy—there is a chance that the changes can be accompanied by anxiety and depression simply due to how hormones and neurotransmitters function in tandem," says Dr. McCabe.

But there's a lot more to consider when it comes to mental health conditions that can occur postpartum.

“It's crucial to remember that postpartum depression and anxiety are complex conditions influenced by a multitude of factors beyond brain structure, including hormonal fluctuations, personal history, and genetic risk factors, as well as social support, and environmental stressors," says Dr. Reichelt.

How To Take Care of Your Brain During Pregnancy

Overall, as these experts point out, the changes taking place in the brain during and after pregnancy should be viewed as beneficial, and necessary.

But there are many things we can also do to take care of our brains while expecting.

• Eat a well-balanced diet: Try and eat foods high in omega-3 fatty acids, vitamins, and minerals to support healthy brain function.

• Take a prenatal vitamin: Make sure it has folate.

• Remain physically active: Always opt for safe activities, such as walking, swimming, and practicing prenatal yoga, to reduce stress and encourage healthy blood flow to the brain.

• Keep your brain active: Try reading, doing puzzles, or learning a new instrument or language to support brain health.

• Manage stress: This can be done through mindfulness and meditation.

• Avoid harmful substances: That includes alcohol.

Finally, don’t forget about getting adequate rest and relaxation, which are important during pregnancy. Dr. Hafeez also urges pregnant people to get enough sleep to best serve the memory, emotional regulation, and overall cognitive function.

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