Pregnancy is a unique time of neuroplasticity in life. Recently,susana carmonaet alA longitudinal study that tracked changes in the cerebral cortex during pregnancy in 110 first-time pregnancies found that maternal cortical volume was lower in late pregnancy than in the control group, but gradually decreased in the early postpartum period. The default mode and frontal lobe network show a lower-than-expected increase in volume, suggesting that the decrease may be more persistent. In addition, mothers who underwent scheduled caesarean sections showed different cortical trajectories. The data suggest that the dynamic trajectory of cortical reduction during pregnancy is attenuated in the postpartum period, with the rate varying depending on the brain network and the type of delivery.
Their results were published in the latest issuenature neurosciencemagazine, called“women’s neuroplasticity during gestation, childbirth and postpartum”
Pregnancy affects all systems of the mother's body. Recent studies have shown that the brain undergoes structural and functional adjustments during pregnancy. Techniques such as magnetic resonance imaging reveal dynamic changes in maternal cerebral cortex volume before and after pregnancy, including an initial decrease and an increase after delivery. Although the studies seem contradictory, they are consistent with the dynamic evolution of brain volume, decreasing during pregnancy and increasing after childbirth. The study tracked first-time maternal brain changes through a longitudinal design, and preliminary evidence suggests that the type of delivery may influence this trajectory (Figure 1 is the participant presentation).
Transverse and longitudinal cortical differences
During the late pregnancy (PRG), the mother's whole cerebral cortex volume and thickness were significantly lower than those of the control group (see Figure 2A). The analysis showed that there were group differences in the main effects in cortical thickness(See Figure 2b). These differences are widely distributed and include the midline region from the medial forehead back to the anterior and posterior cingulate, as well as the lateral regions of the anterior and posterior central sulcus, the dorsal prefrontal cortex, and the temporal lobe node. In the postpartum stage, the volume and thickness of the mother's cortex remained lower than that of the control group (see Figure 2A). These differences overlap with the brain regions affected during pregnancy, but have less expansion (see Figure 2B).
Compared with the control group, the mother's whole cerebral cortex volume, thickness, and surface area showed a significant increase in the PRG to POST stage(See Figure 3a).The increase in prg-to-postertic mainly affects cortical volume (see Figure 3B). These increases were widely distributed, and an increase in maternal prg-to-post cortical thickness and surface area was also observed, albeit to a lesser extent (see Figure 3B).
In the postpartum period, changes in cortical volume, thickness, and surface area of the mother's brain were positively correlated with the percentage of postpartum time (Figure 3c). Supplemental analyses considered the effects of potentially confounding variables, such as participants' age, total intracranial volume, and group differences in sleep quality and perceived stress.
The effect size and spatial correspondence were evaluated using seven large functional brain networks of YEO as a benchmark (Figure 4). In the later stages of pregnancy, the mother's cortical volume decreases significantly across all functional networks. However, in the early postpartum period, the reduction in cortical volume was more pronounced in the mother's default mode network. The volume of the coronal cortex was significantly increased in the attention network, and the volume of the subcortical cortex in the frontal lobe and the default mode network was significantly increased.
In independent datasets, important neuroanatomical findings were validated. Specifically, in late pregnancy, the primary and replicate datasets presented a higher spatial correspondence than chance in cortical volume and thickness effect size plots (see Figure 5a). In addition, despite the small number of subjects who replicated the dataset and the relatively low statistical power, the cortical thickness of the mother in the inner wall region was also significantly lower. The authors similarly observed an upper opportunistic spatial correspondence of cortical volume and surface area (see Figure 5B).
Neuropsychological variables
In the postpartum period, maternal perceived stress, sleep problems, depressive symptoms, and maternal attachment scores were significantly higher than those in pregnancy. Compared with the control group, mothers' perceived stress and sleep quality deteriorated significantly during the PRG to POST period. Figure 6 reveals the association between maternal neuropsychological scores, highlighting the relationship between pregnancy anxiety and childbirth experience and postpartum parenting stress. These findings have important implications for understanding neuropsychological factors in postpartum mental health.
Cortical indicators as a function of childbirth
The authors compared cortical trajectories of mothers initiating labor and planning caesarean section. Mothers who were scheduled for caesarean section showed greater prg-to-post whole-brain growth in cortical volume, thickness, and surface area than mothers who started labor, even after other factors were considered. Of note, the mode of delivery had no effect on cortical volume, thickness, and surface area of the whole brain and maxima, either in pregnancy or postpartum. Among mothers at the start of labor, there were no significant differences in these areas between labour and emergency caesarean section. Figure 7 provides a more detailed comparison and visualization.
Summary
This study reveals the effects of childbirth on neuroplasticity in the mother's brain, highlighting that immune and endocrine adaptations may induce neurological changes. The experience of childbirth may lead to further cortical shrinkage, suggesting that the perinatal period is a sensitive time for female neuroplasticity. Studies were related to maternal attachment, well-being, and depression. Although the sample was from Western-educated mothers, these findings shed light for the study of a broader sample of mothers. Overall, the perinatal period is positioned as a period of female neuroplasticity that deserves in-depth study and protection.