A pioneering study led by researchers from the Universitat Autònoma de Barcelona (UAB), in collaboration with renowned institutions like the Gregorio Marañón Health Research Institute and the Hospital del Mar Research Institute, has conducted the first-ever longitudinal analysis of the brain structure of women during pregnancy using cutting-edge neuroimaging techniques. Published in Nature Communications, this research unveils crucial findings about how a woman’s brain changes during pregnancy, specifically in areas related to social cognition, emotion regulation, and maternal bonding.
The research, which involved a cohort of 179 women, marks a significant step forward in the exploration of maternal brain changes. Unlike previous studies that mostly focused on post-birth alterations, this study carefully tracked the physical changes in the brains of women during the second and third trimesters of pregnancy and the first six months postpartum. Notably, the inclusion of a control group of non-gestational mothers—partners of pregnant women—allowed the researchers to distinguish biological brain changes related specifically to pregnancy from those induced by motherhood itself.
The Study Design and Its Novelty
The team, led by first authors Camila Servin-Barthet and Magdalena Martínez-García, and coordinated by Òscar Vilarroya and Susana Carmona, used advanced Magnetic Resonance Imaging (MRI) scans to explore how the brains of 179 women evolved across various stages of pregnancy and postpartum. Before conception, MRI scans of participants’ brains were taken as a baseline. The subjects were followed throughout their pregnancy and postpartum periods, allowing the researchers to track how the structure of their brains changed over time.
What makes this study particularly unique is the inclusion of a control group made up of non-gestational mothers—women whose partners were pregnant. The research showed that the brain alterations identified during pregnancy were not solely attributable to the experience of becoming a mother, but rather the biological effects of pregnancy itself. This approach distinguishes the hormonal and physical changes induced by the pregnancy from those associated with the transition into motherhood.
Key Findings: Brain Volume Reduction and Recovery
One of the standout findings of the study is the significant reduction of gray matter volume in the brain during pregnancy. On average, the participants experienced a reduction of approximately 4.9% in gray matter volume, with particular reductions observed in brain regions linked to social cognition, such as those responsible for processing emotional information, empathy, and decision-making. This decrease was observed in 94% of the brain, highlighting how pervasive these brain changes are.
What’s remarkable is that these changes were not permanent. The brain showed partial recovery of gray matter volume postpartum, as early as the first six months after birth. While the decline in gray matter during pregnancy may seem concerning at first, the subsequent recovery underscores the dynamic and adaptive nature of the maternal brain during the prenatal and postpartum periods.
These findings build on growing evidence that pregnancy prompts substantial neurobiological changes in women, particularly in regions of the brain responsible for social and maternal behaviors. The changes likely enhance women’s ability to bond with their newborns, promote caregiving behaviors, and enable the overall transition to motherhood.
Hormonal Influence: Estrogens and the Brain
The study also delved into the role that hormones, particularly estrogens, play in these brain changes. During pregnancy, there is an exponential increase in estrogen levels, with two forms of estrogen—estriol-3-sulfate and estrone-sulfate—acting as key influencers. These hormones increase sharply throughout pregnancy and then drop back to baseline levels following childbirth. The researchers found a strong correlation between the increase and subsequent decrease in estrogen levels and the corresponding reduction and recovery of gray matter volume in the brain.
Women who experienced a greater rise in estrogen levels during pregnancy tended to experience a more significant decrease in gray matter, followed by a more pronounced recovery in the postpartum period. This direct relationship between hormonal fluctuations and structural brain changes offers important insight into the neurobiology of pregnancy and early motherhood.
The Impact on Maternal Behavior and Bonding
An even more intriguing aspect of the study is its investigation into the link between brain changes and maternal behavior. The researchers found that women who experienced a greater recovery in gray matter volume postpartum reported stronger feelings of bonding with their infant at six months after birth. The study indicated that hormonal fluctuations and brain structure changes may not only support the biological changes occurring during pregnancy but also contribute to emotional processes vital for forming the maternal-child bond.
Further, maternal well-being during the postpartum period was identified as a key factor that positively influenced the connection between brain changes and maternal attachment. The findings suggest that women who were psychologically well-adjusted during the early postpartum period demonstrated stronger bonding with their babies, highlighting the complex relationship between brain physiology and mental health during the transition to motherhood.
The Significance and Future Directions of This Research
The comprehensive data from this study provide the first holistic understanding of normative brain changes during pregnancy and the early postpartum period, offering vital insights into how pregnancy shapes the maternal brain. The research also sheds light on the lasting impact of hormonal shifts on brain function and structure, specifically in areas critical for social cognition and emotional regulation.
By distinguishing the biological brain changes associated with pregnancy from those caused by the experience of motherhood, the study sets a new benchmark for understanding maternal neurobiology. This foundation is crucial for future research that aims to further explore pregnancy-specific brain changes and their long-term effects on maternal and child health.
Moreover, the study opens up possibilities for investigating the effects of clinical conditions, such as postpartum depression, on brain structure and functioning. Given that these conditions can greatly affect maternal well-being and maternal-infant bonding, understanding the underlying neurobiological mechanisms is key for improving mental health outcomes for mothers and their children.
Conclusion: A Step Towards a Deeper Understanding of the Maternal Brain
This first-of-its-kind study offers a breakthrough in understanding how pregnancy reshapes the maternal brain and provides valuable insights into the neurobiology of motherhood. By analyzing brain changes across critical stages of pregnancy and postpartum, the research establishes a crucial reference point for both academic study and clinical applications.
With a sample size large enough to allow meaningful conclusions and a methodological rigor that distinguishes pregnancy-related brain changes from those influenced by maternal experience, the findings of this study represent an exciting advance in the field. Future research will likely build on these discoveries, applying them to diverse populations and exploring how different clinical conditions might influence the brain changes associated with becoming a mother.
Ultimately, this research contributes not only to our scientific knowledge of maternal neurobiology but also paves the way for potential therapeutic interventions that can improve mental and emotional health during one of the most transformative periods of life. It is an essential step toward better understanding the maternal brain, a frontier in scientific research that holds significant promise for improving maternal and child health in the years to come.
Reference: Camila Servin-Barthet et al, Pregnancy entails a U-shaped trajectory in human brain structure linked to hormones and maternal attachment, Nature Communications (2025). DOI: 10.1038/s41467-025-55830-0