October 23, 2024, 3:22 pm | Read time: 5 minutes
Tiredness, nausea, and vomiting are probably the most classic physical symptoms when you think of pregnancy. But the body of pregnant women apparently changes in more ways than previously known – including in the brain. Scientists at the University of California recently presented the first detailed map of the human brain during pregnancy.
During pregnancy, the body undergoes rapid physiological changes to prepare for birth and breastfeeding – this is well known. What has remained unanswered until now, however, is what the far-reaching hormonal changes during pregnancy do to the brain. A team of neuroscientists at UC Santa Barbara have now been able to shed light on this little-researched area with the first-ever map of the human brain during pregnancy.
Overview
Hormones lead to neuronal remodeling
The authors of the study explain that profound physiological changes during pregnancy are made possible by a 100- to 1000-fold increase in hormone production. The hormones involved include estrogen and progesterone. These hormones also lead to a considerable restructuring of the central nervous system. Previous findings from animal models and human studies indicate that pregnancy is a phase of remarkable neuroplasticity. In other words, individual nerve cells and even entire areas of the brain are remodeled1
Laura Pritschet, lead author of the study, explains in a press release from the university: “We wanted to investigate the course of brain changes specifically within the pregnancy phase.” She also explained that although previous studies had taken snapshots of the brain before and after pregnancy, the pregnant brain had never before been observed in the midst of metamorphosis.2
Pregnant participant underwent 26 MRI scans
For the detailed brain imaging, the scientists worked with a healthy 38-year-old first-time mother who was artificially inseminated via in vitro fertilization (IVF). Her brain was first scanned by magnetic resonance imaging (MRI) three weeks before conception. She also underwent further scans over the course of her pregnancy until two years after giving birth. In total, the researchers imaged her brain 26 times. They also took blood samples from their test subject during the study period.
Processes in the brain are similar to those during puberty
The most obvious change that the scientists observed in their test subject’s brain was a decrease in the volume of gray matter, the wrinkled outer part of the brain. With the increase in hormone production during pregnancy, the volume of gray matter decreased. And this was the case in 80 percent of the 400 brain regions examined. Even if this sounds frightening at first, it is not necessarily a bad thing, the scientists emphasized. This change could indicate a “fine-tuning” of the brain circuits, similar to the processes in the brains of young adults during puberty. Pregnancy probably reflects a further phase of cortical refinement.
While gray matter decreased, white matter increased
A less obvious but equally significant observation made by the researchers was a significant increase in white matter. This lies deeper in the brain and is generally responsible for communication between brain regions. While the decrease in gray matter continued long after birth, the increase in white matter was short-lived. Its volume peaked in the second trimester. It then returned to pre-pregnancy levels around the time of birth. According to the scientists, this effect has never been seen before in before-and-after scans. This allows a better assessment of how dynamic the brain can be in a relatively short period of time. Thus, the “choreographed change” of the maternal brain, as study author Emily Jacobs called the restructuring, could support adjustments in behavior during parenthood.
Classification of the study
The study results are significant because they are the first to provide detailed images of the brain before, during, and after pregnancy and reveal changes that millions of women go through every year. As the series of studies only involved one test subject, it remains unclear to what extent the results could be transferred to the general population. Rather, the study provides an important basis for conducting further imaging studies during pregnancy with a larger number of participants.
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Future research on the human brain
Lead author Pritschet explained that pregnancies should not be a niche topic in neuroscience. The findings would “deepen our general understanding of the human brain, including its aging process.” She also hopes to break the dogma that women are particularly fragile during pregnancy.
The data obtained in the current study will now serve as a starting point for future studies to find out whether the extent or speed of the changes in the brain indicates a woman’s risk of postpartum depression. This is a neurological disorder that affects around one in five women. “There are now FDA-approved treatments for postpartum depression,” Pritschet said, “but early detection remains difficult. The more we learn about the maternal brain, the better our chances of providing relief.”
With the support of the Ann S. Bowers Women’s Brain Health Initiative, which Jacobs leads, her team plans to build on these findings as part of the Maternal Brain Project. More women and their partners will be included in ongoing studies. Jacobs has a clear vision: “Together, we have the opportunity to address some of the most pressing and least understood issues in women’s health.”