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Pregnancy involves radical hormone surges and biological adaptations, but the effects on the brain are still unknown. In this study a team of researchers compared the structure of the brain of women before and after their first pregnancy. This is the first research to show that pregnancy involves long-lasting changes – at least for two years post-partum – in the morphology of a woman's brain.

Using magnetic resonance imaging, the scientists have been able to show that the brains of women who have undergone a first pregnancy present significant changes in regions associated with social relations.

The researchers believe that such changes correspond to an adaptive process of functional specialization towards motherhood. “These changes may reflect, at least in part, a mechanism of synaptic pruning, which also takes place in adolescence, where weak synapses are eliminated giving way to more efficient and specialized neural networks”, says Elseline Hoekzema, co-lead author of the article. According to Erika Barba, the other co-lead author, “these changes concern brain areas associated

In order to conduct the study, researchers compared magnetic resonance images of 25 first-time mothers before and after their pregnancy, of 19 male partners, and of a control group formed by 20 women who were not and had never been pregnant and 17 male partners. They gathered information about the participants during five years and four months.

The results of the research directed by Òscar Vilarroya and Susanna Carmona demonstrated changes in the medial frontal and posterior cortex line, as well as in specific sections of, mainly, prefrontal and temporal cortex in pregnant women. “These areas correspond to a great extent with a network associated with processes involved in social cognition and self-focused processing”, indicates Susanna Carmona, coordinator of neuroimaging section in the Medical Imaging Laboratory, that has researchers from the Department of Bioengineering and Aerospace Engineering of UC3M and the Institute of Sanitary Research in Gregorio Maranon Hospital.

The analyses of the study determine with great reliability whether any woman from the study had been pregnant depending on the changes in the brain structure. They were even able to predict the mother's attachment to her baby in the postpartum period based on these brain changes.

The study took into account variations in both women who had undergone fertility treatments and women who had become pregnant naturally, and these changes were practically identical in both groups.

Researchers did not observe any changes in memory or other cognitive functions during the pregnancies and therefore believe that “point to an adaptive process related to the benefits of better detecting the needs of the child, such as identifying the newborn's emotional state. Moreover, they provide primary clues regarding the neural basis of motherhood, perinatal mental health and brain plasticity in general”, says Oscar Vilarroya.

Elseline Hoekzema (researcher at the UAB at the time of the study, but currently working at Leiden University) and Erika Barba-Müller (UAB) are the lead authors of the article published in Nature Neuroscience.

The study was directed by Susana Carmona [researcher at the UAB at the time of the study and now at the Universidad Carlos III de Madrid, IiSGM and affiliated to the CIBER of Mental Health (CIBERSAM)] and co-directed  by Òscar Vilarroya, from the Cognitive Neuroscience Research Unit of the Department of Psychiatry and Legal Medicine at the UAB, and coordinator of the research group Neuroimaging of Mental Disorders at the IMIM Foundation. Also collaborating in the research were Cristina Pozzobon, Florencio Lucco and Agustín Ballesteros (Valencian Infertility Institute, IVI); Marisol Picado (Hospital Clínic); Eveline A. Crone (Leiden University); David García-García and Manuel Desco (University Carlos III and Instituto de Investigación Sanitaria Gregorio Marañón, Madrid); and Juan Carlos Soliva and Adolf Tobeña (UAB).