During pregnancy, women undergo various changes in body and behavior. A recent Nature communications The study evaluated pre-pregnancy and post-pregnancy brain scans to better understand changes in gray matter architecture, diffusion metrics of neural metabolite concentration, and the temporal coherence of neural networks. In addition, biological factors associated with these changes were evaluated in this study.
Pregnant women undergo a monumental transition related to a cascade of endocrine changes and various adaptations in the body. Almost all bodily systems change during pregnancy, and some physiological changes remain constant for decades after delivery. Limited evidence has been documented on changes in the human brain during pregnancy and beyond.
Several non-human animal models have indicated a correlation between reproduction and brain plasticity. These studies have indicated important changes in the mammalian brain and behavior.
According to a recent study, pregnant women change the structure of the gray matter of the human brain. The present study went a step further to analyze changes in pregnant women’s neural metabolite concentrations, neural network organization, and white matter microstructure using a full prospective study cohort.
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Four longitudinal experimental sessions were included in this study, and participants were followed up from preconception to the late postpartum period. Analytical tools, such as diffusion-weighted imaging, anatomical magnetic resonance imaging (MRI), resting-state functional MRI acquisitions, and 1H nuclear magnetic resonance spectroscopy, have been used to study the effect of pregnancy on the human brain.
Changes in hormonal profiles were assessed to analyze the mechanism underlying pregnancy-related neuroplasticity. Maternal hormone levels were determined using biological samples collected every four weeks of pregnancy. The participants’ sleep patterns and stress levels were also recorded.
The changes in brain scans over the study period were recorded in a graph. A specific structural and functional brain plasticity has been observed that could contribute to maternal adaptability during pregnancy.
Compared to non-pregnant women, a distinct gray matter architecture was found in pregnant women. In pregnant women, gray matter volume reduction was observed, affecting the anterior and posterior midline cortex and specific parts of the bilateral lateral and temporal prefrontal cortex.
Magnetic resonance spectroscopy, diffusion-weighted imaging, and resting-state functional magnetic resonance imaging data revealed no significant differences in white matter diffusion metrics or volume between the pregnant and nulliparous (control) groups. This finding indicates that a woman’s white matter anatomy remains stable throughout pregnancy.
The fluctuations of sex steroid hormones were selectively strong for some components of the brain, i.e. steroid hormones affect the gray matter of the brain much more than the structure of the white matter. Magnetic resonance spectroscopy data revealed no changes in neural metabolite concentrations during pregnancy.
The Default Mode Network (DMN) corresponds to a group of highly consistently activated brains that remain highly active even without a specific task. Hence, DMN reflects the basic activity of an individual’s brain. It is also heavily engaged with higher order social processes, such as social evaluation, social cognition, and empathy.
MRI data on the resting state of women deciphered the neural network organization of pregnant women. This analysis revealed a selective increase in DMN in pregnant women who were between sessions, compared with the control group. Although structural brain changes were most evident in the DMN, frontoparietal brain regions associated with higher-order cognitive tasks (eg, cognitive functions) were also affected.
It is important for new mothers to focus on their baby’s needs and feelings and to understand their emotions. Consequently, several studies have indicated a functional change in the DMN. Furthermore, resting-state functional connectivity in mothers was related to maternal behavior.
The current study hypothesized that pregnancy-associated structural and functional changes in the DMN change an individual’s neuronal structure, which prepares women for motherhood. Interestingly, neural changes in the DMN were observed to correlate with the degree of mother-infant bonding.
Some of the factors that drive pregnancy-related brain plasticity are pregnancy hormones. For example, estradiol levels, particularly in the third trimester, were associated with changes in brain structure. Sleep, osmotic effects, breastfeeding, stress or the type of delivery have not been linked to any structural or functional changes in the brain during pregnancy. The unparalleled exposure to estrogen during the last stage of pregnancy has been found to affect pregnancy-related structural neuroplasticity.
Analytical data from pregnant women indicated structural and functional plasticity within the DMN, suggesting that mothers experience changes in the basal state of the brain. Functional changes in the DMN have been associated with child-directed processes, whereas structural changes in the brain are related to simulations of preparatory behavior. In the future, a wider range of potential regulatory factors (for example, nutrition, genetic markers, environmental changes, and exercise) will need to be evaluated to better understand their role in influencing brain processes during pregnancy.