Pregnant women show a widespread reduction in gray matter within the brain.

During pregnancy and childbirth, the female body undergoes significant changes. Authors of a previous scientific article reported that pregnancy accelerates biological aging, but with the arrival of the baby, this process reverses for the mother. In another study, American neurologists observed how the brain structure of a healthy 38-year-old woman transformed from pre-conception through pregnancy and after childbirth.

Recently, Spanish doctors contributed to this research. Using magnetic resonance imaging, they tracked the transformations in the brains of 127 pregnant women before conception, during pregnancy, and after childbirth—at one month and six months postpartum. The data was also compared with MRI scans from control groups, which included 20 non-pregnant mothers and 32 women who had never given birth.

Additionally, the examination program included the collection of urine samples to determine hormonal levels and the completion of questionnaires to assess psychological well-being and maternal attachment. An article about the study was recently published in the journal Nature Communications.

Researchers focused on the volume of gray matter, which is considered a key indicator of structural changes in the brain and is also linked to a person's IQ. The analysis of MRI data revealed a distinct U-shaped trajectory: the decrease in gray matter was noticeable by the second trimester, and by the end of pregnancy, the decline peaked. The volume partially recovered six months after childbirth.

The most pronounced changes were observed in structures such as the brain's default mode network and the frontal-parietal internal brain network. These areas are associated with social cognition and decision-making processes. The researchers emphasized that such fluctuations were characteristic only of pregnant women and were not found in non-pregnant mothers or women who had never given birth.

A close connection was also found between changes in gray matter and shifts in hormonal levels. The levels of two estrogens—estriol sulfate and estrone sulfate—changed in parallel, following an inverted U trajectory: increasing during pregnancy and sharply declining after childbirth. Considering this, the scientists suggested that estrogens play a crucial role in stimulating brain structure transformation during pregnancy.

Commenting on the study to PsyPost, one of its authors, Oscar Vilarroya, noted that during pregnancy, the reduction in gray matter affected 94% of its volume, with a loss of up to 5%. After childbirth, partial recovery was observed. The results of psychological questionnaires completed by participants showed that the reverse structural changes in the brain correlated with an increase in maternal attachment to the child.

Discussing the importance of their work, the scientists stated that it sheds light on the complex interplay between hormonal, neurobiological, and behavioral changes as the body prepares for motherhood. These discoveries contribute to a scientific understanding of these processes and the improvement of maternal healthcare.