Pregnancy Alters Mothers’ Brains. These New Findings Are Revealing How

Research indicates that “baby brain” isn’t the deficit it’s often portrayed as. Neural changes during pregnancy may prepare expectant mothers to better connect with their children and improve social cognition.

I rummaged through every drawer, basket, and countertop. I even emptied my purse and checked my coat pockets. No luck. My husband’s keys had vanished. It wasn’t until I stepped outside half an hour later that I spotted them, hanging from the lock on our front door. Such absent-mindedness is not typical for me—and it’s incredibly exasperating. Since I became pregnant with my first child in early 2024, my brain feels altered. I frequently lose my thoughts and struggle to find words that seem just out of reach. Deep analytical thinking can be draining.

This isn’t out of the ordinary. Up to 80 percent of expectant mothers report memory challenges, and many continue to face these difficulties into the early postpartum period. Often labeled as “mommy brain” or “baby brain,” these experiences of mental fog, forgetfulness, and concentration issues are typically viewed and felt as deficits. However, recent research is uncovering what is genuinely occurring in women’s brains during this phase: Significant changes in brain structure and function are taking place, and these renovations appear to be largely beneficial.

During pregnancy, the body is inundated with hormones—particularly estrogen and progesterone—that aid fetal development and help establish a secure environment for the baby. However, these changes, among other physiological shifts, also affect the mind. Mothers’ brains appear different, and these alterations enhance their connection with and understanding of their infants.

“We women were correct,” asserts Susana Carmona, a neuroscientist and director of the neuromaternal lab at Hospital Gregorio Marañón in Madrid. “We sensed that something occurs in our brains, or the way we perceive our surroundings and our emotions. Now, we have neuroimaging evidence that powerfully illustrates how motherhood transforms you entirely.”

A reconfiguration of the brain

Neuroscientists are gaining vital insights from mothers. A key recent finding: The brain doesn’t cease to develop and evolve after adolescence. Instead, neuroplasticity, or the brain’s capacity to reorganize itself, persists well into adulthood.

Monitor the brain of a pregnant woman, and you’ll observe substantial structural changes throughout the trimesters, including a reduction in gray matter volume, which constitutes the brain’s outer layer and aids information processing. There’s a decline in cortical volume, associated with cognitive skills, memory, and sensory processing. You may also notice a decrease in the production of new neurons in the hippocampus, linked with learning and memory.

While the loss of any brain matter might sound concerning, researchers emphasize this is a reconfiguration, not a reduction. “The best analogy is to liken it to adolescence, during which the brain undergoes a similar transformation, influenced by significant endocrine changes, and once it’s transformed, that’s when the potential emerges,” states Emily Jacobs, a neuroscientist at the University of California, Santa Barbara, and director of the Ann S. Bowers Women’s Brain Health Initiative. “It becomes capable of new functions, new behaviors that it had not encountered before.”

Jacobs led a 2024 research study where her team collected brain scans and blood samples from a fellow neurobiologist from preconception through two years postpartum. The study revealed the “highly dynamic changes that unfold in a human brain throughout pregnancy,” including the gray matter and cortical volume decrease. They also identified improved microstructural integrity of white matter, notably in the pathways that connect areas responsible for emotional and visual processing. An additional 20 women have participated in this protocol, and their results are expected to be released soon, according to Jacobs.

These brain modifications may serve a functional purpose. A partial rebound in gray matter volume in the early months of motherhood is believed to aid in mother-infant bonding. A paper from 2025 authored by Carmona and colleagues demonstrated that women who experienced the most significant brain remodeling also exhibited the highest scores in infant attachment.

Expectant mothers’ skills in interpreting facial expressions, particularly those that are fearful, angry, or sad, may improve later in pregnancy. Connectivity in the Default Mode Network, which impacts our self-perception and social cognition, has also revealed increased connectivity during and after pregnancy. Evidence suggests improved memory postpartum for both humans and rats, with human brains appearing younger post-childbirth than before conception.

“We’ve even described parenthood itself as a form of enrichment and cognitive enhancement—indicating that there’s potential for growth. If evidence shows that efficiency arises from the reorganization occurring… it suggests a positive outcome from becoming a parent,” comments Helena Rutherford, a psychologist at Yale University and director of the Before and After Baby Lab. She emphasizes that such benefits are seldom discussed. “It’s often framed negatively.”

These effects seem to have lasting impacts, according to Elseline Hoekzema, head of the Pregnancy Brain Lab at Amsterdam University Medical Center. Certain adaptations, such as diminished gray matter volume, can persist for up to six years or longer; meanwhile, functional changes, including the behavior of the Default Mode Network, return to nearly preconception levels within the first postpartum year. (Women who breastfeed for extended periods may retain these functional changes longer.)

In subsequent pregnancies, these adaptations become refined, with brain networks guiding attention and sensory response exhibiting even more pronounced changes, as reported by Hoekzema and colleagues in a recent study.

“We have observed remarkably consistent changes across diverse women,” Hoekzema remarks. Longitudinal studies following women through pregnancy in the United States, Spain, the Netherlands, and Germany have yielded results akin to Jacobs’ research, indicating that brain alterations are widespread.

What’s also prevalent: the confusion that pregnant women and new mothers often experience as these transformations occur. “Her brain is undergoing a change,” Hoekzema notes, “but this will normalize, and it appears to serve a beneficial purpose.”

The influence of hormones

Chelsea Conaboy believed she was well-prepared for her first child in 2015. She read books, attended classes, toured the hospital, and felt financially ready for a child. She and her husband “checked all those boxes,” she recalls, “yet I was still completely unprepared for the realities of new motherhood.”

In those early months, anxiety and worry accompanied the health and science journalist—a typical reaction to a significant life shift and the increased cortisol levels that support the fetus. While hormones are a crucial topic of discussion during pregnancy as doctors monitor the developing baby, OB/GYNs often overlook the fact that these hormones also lead to significant brain changes for the mother.

“These [brain] alterations can induce anxiety, but they also represent significant, lifelong changes that we seldom discuss,” Conaboy states, author of Mother Brain: How Neuroscience Is Rewriting the Story of Parenthood. “This wasn’t included in my prenatal education at all,” she continues. “Why weren’t expectant parents provided this information to help them comprehend their own transitions and how their brains function?”

Pregnancy triggers a 100- to 1,000-fold surge in hormone production, resulting in changes across the entire body, such as increased oxygen consumption, metabolism, blood volume, and shifts in the nervous and immune systems. These chemical messengers also contribute to the brain’s reorganization.

“Hormones function as the sculptor,” Jacobs explains. “They shape the brain, enabling it to become exceptionally efficient, highly attuned to this new phase of life.” A report from 2020 by Jacobs illustrated that brain circuits responsible for memory and mind-wandering are enhanced when estrogen levels peak during the menstrual cycle, which may provide insights regarding pregnancy. “The insights gleaned from understanding how the brain reacts to smaller fluctuations such as the menstrual cycle can foreshadow what we might observe during pregnancy,” Jacobs elaborates. “The two are interconnected.”

Much of the investigation into these hormone-driven changes in humans has surfaced only in the last decade or so, though animal studies have revealed these trends for a far longer time. They indicate that gestational hormones foster caregiving behaviors and strengthen mother-infant bonds. A 2023 study, for instance, revealed a restructuring of hypothalamic neurons in pregnant mice that drove the emergence of maternal behaviors, “in anticipation of future behavioral requirements.” Another study published last year found that the pre-pregnancy estrous cycle in female mice influenced the structure and function of neurons in the hippocampus.

Together, this research demonstrates the extent of how pregnancy influences the brain. “This is one of the most significant effects I have ever encountered in neuroscience,” asserts Jacobs, “the magnitude of transformation over such a short duration.”

Many inquiries persist

The memory difficulties and mental fog I faced postpartum may not directly stem from these brain changes. Research has yet to clarify whether, and how, the alterations in the brain during pregnancy correlate with behavior or women’s perceived declines in cognitive performance. “Despite observing these imaging variations, we are still unsure what they signify behaviorally,” notes Sasha Davies, a psychologist at the Cairnmillar Institute in Australia. “And when we investigate cognitive functioning, we can’t definitively determine the daily effects, if any.”

Some of these challenges may arise from significant lifestyle shifts during this period, such as sleep deprivation and the mental burden associated with pregnancy and parenting.

Researchers are undertaking longitudinal studies to gain deeper insights into these inquiries and others, including the potential effects of age, race, and other demographic factors. Much of the published literature in this area has lacked racial diversity, as researchers noted last year.

Investigating “mommy brain” offers a potentially life-saving angle: it may provide insight into postpartum depression. This condition affects one in eight women in the U.S., with around half of mothers exhibiting symptoms remaining undiagnosed. The U.S. has the highest maternal mortality rate among developed nations, with suicide being one of the leading causes of postpartum deaths. “If parents are facing difficulties, there will be ramifications for the developing child too. Hence, we are perpetuating risk across generations when we could be providing much more support,” remarks Rutherford, the Yale psychologist. Recent findings, she notes, indicate that the transition into parenthood is “a time that requires more discussion.”

As laboratories worldwide enhance their databases relating to pregnancy-associated brain changes, hormones, and more, this could help predict the onset of postpartum depression and recognize other indicators of maternal health.

“This research is urgent,” emphasizes neuroscientist Carmona. “It doesn’t just impact the individual’s economic situation; it also affects the growth of the child and the integrity of the entire family system.”