Pregnancy-related brain changes may help new mothers

By employees of Brain and Behavior

Pregnancy is a time of profound changes in the female body, including the endocrine system – the system that secretes and regulates hormones. Changes in female sex hormones such as estrogen orchestrate countless adjustments throughout the body, including the brain. Yet there is remarkably little data reflecting the impact of the reproductive process on the female human brain.

To address this, in 2017 BBRF Young Investigator Elseline Hoekzema, Ph.D., of the University Medical Center of Amsterdam and the University of Leiden, the Netherlands, led a team that recruited 80 women of childbearing age, half of whom became pregnant over time. period of the study, and a matching group that was not pregnant at that time.

Dr. Hoekzema and colleagues used four technologies to examine brain structure and function in these women at four time points. Tests were performed on all women at baseline, which was before conception for the women who became pregnant; and then sometimes corresponding to the late pregnancy, postpartum, and late postpartum period among the participants who became pregnant.

These tests enabled the team to assess brain structure and function across the four time periods and supported a series of key findings about how pregnancy affects resting brain activity, the structure of the brain’s white and gray matter, and levels of neural metabolites – affect molecules. generated by or as a result of metabolic processes taking place in brain cells.

Broadly speaking, the team reports Nature communication, said their data revealed “pronounced and selective structural and functional” changes in brain plasticity, “that may confer adaptive benefits” that influence maternal behavior in forging bonds with a new child. Plasticity refers to changes in the strength of connections between neurons and is a key factor in how well the brain functions, for example in learning, memory, and the ability to respond and adapt to changing physical or environmental conditions. Deficiencies in neuroplasticity have also been linked to depression and other psychiatric conditions.

The tests performed at baseline showed that there were no pre-existing differences in brain gray matter volume between women in the two groups. Gray matter roughly corresponds to parts of the brain composed of neuronal cell bodies; white matter refers to the structures such as axons that connect neurons into complex networks.

Using data from structural MRI scans each woman received over the course of the study, the team was able to confirm its own previous finding, which showed that women who were pregnant and the postpartum period discounts described in the volume of their gray matter as “highly significant” with “very large effects”. The new findings confirmed not only the magnitude of the reductions previously observed, but also the locations in the brain where they appear to be most prominent.

Resting-state fMRI scans showed that despite the reduction in gray matter in women who were pregnant or in the postpartum phase (compared to controls who were not pregnant at these time points), there was a remarkable “increase in functional connectivity” that was evident in the brain’s default mode network (DMN). The DMN regulates brain activity at times when an individual is not focused on the outside world. In particular, the team found that reproductive processes improved the “temporal coherence” of the DMN.

Another brain scan technology called diffusion tensor imaging revealed that there was no significant change in white matter structure in the pregnant/postpartum women compared to those in the control group. Similarly, measurements of neural metabolite concentrations revealed no strong changes.

Pregnancy Essential Reads

Perhaps the study’s most important finding was that pregnancy-related neural changes were likely linked to stimulating behavioral and physical adaptations that new mothers normally make to prepare for motherhood. For example, pregnancy-related neural changes have been associated with changes in mothers’ physiological responses to infants, to nesting behavior, and to bonding with newborns in the postpartum period.

While the observed changes in brain structure were maintained, the increase in DMN coherence gradually returned to pre-pregnancy levels during the postpartum period. Total duration of breastfeeding correlated positively with gains in DMN coherence, suggesting to the team that “prolonged breastfeeding may stimulate long-term maintenance of pregnancy-related neural changes.”

During the perinatal period, changes in the DMN, which plays a key role in self-perception, may even “underlie transformations in the neural representation of the self when you become a mother,” the researchers speculated. Sex hormones and especially estrogen seem to contribute to these adaptive brain changes. Broadly speaking, they said, “our findings suggest that pregnancy-related neuroplasticity plays a role in maternal psychological and physiological pregnancy processes that help a woman prepare for the arrival of her baby” and in “the establishment of the mother-child relationship.” dyad.”

Pregnancy-related brain changes may help new mothers

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