Pregnancy's influence on the brain, as suggested by recent studies.
Certain parts of the brain might shrink in size during pregnancy while enhancing connectivity, with only a handful of brain areas remaining unaffected by the transition into motherhood, as per a study released on Monday in the journal Nature Neuroscience.
The research is based on the examination of a single healthy 38-year-old woman from three weeks prior to conception up until two years following her child's birth. Dr. Elizabeth R. Chrastil, a professor at the University of California, Santa Barbara, chose to participate in this study after previously doing so in similar research.
"There is still so much about the neurobiology of pregnancy that remains a mystery," said Dr. Emily Jacobs, the study's senior author and an associate professor in the department of psychological and brain sciences at UC Santa Barbara, in a discussion about the study. "It's not due to women being overly complex; rather, it's because the biomedical sciences have historically overlooked women's health."
EXPLORE SIMPLY: Why You're Not a Bad Mother
Approximately 85% of sexually active women who do not utilize any form of birth control can expect to become pregnant within a year, and around 208 million women become pregnant annually.
"The brain is an endocrine organ, and sex hormones are powerful neuromodulators, but much of this knowledge comes from animal studies," Jacobs explained. Human studies frequently rely on brain imaging and endocrine assessments obtained from large groups of individuals at a specific point in time.
"Group averaging techniques cannot reveal how the brain changes from day to day or week to week as hormone levels fluctuate," Jacobs continued. "My lab at UC Santa Barbara utilizes advanced imaging techniques to analyze how the brain responds to significant neuroendocrine transitions, such as the circadian cycle, the menstrual cycle, menopause, and as shown in this study, one of the largest neuroendocrine transitions that a human can experience – pregnancy."
How Pregnancy Alters a Mother's Brain
Jacobs and her colleagues performed 26 MRI scans and blood tests on the first-time mother, then compared the results to brain changes observed in eight non-pregnant control participants.
By the ninth week of pregnancy, the researchers identified widespread decreases in gray matter volume and thickness of the cerebral cortex, especially in regions such as the default mode network, which is associated with social cognitive functions. Gray matter plays a crucial role in sensations and functions such as speech, thought, and memory, and it generally decreases in thickness following its peak during childhood.
The scans also demonstrated increases in cerebrospinal fluid and white matter microstructure during the second and third trimesters, all linked to rising estradiol and progesterone hormone levels. Cerebrospinal fluid is crucial for nourishing, protecting, and removing waste from the brain, while white matter facilitates communication between different brain areas and the processing of information.
Some of the changes, such as cortical volume and thickness, remained two years postpartum, while others reverted to preconception levels by roughly two months postpartum. The woman's gray matter volume change was nearly three times higher than that of the control group.
"This study provides crucial information for future research by offering data that can be used to explore how we can support healthy brain changes during pregnancy (in the mother, which would likely impact the developing fetus)," Dr. Jodi Pawluski, a neuroscientist, therapist, and author based in France, said via email. Pawluski was not involved in the study.
The study "demonstrates the potential of precision imaging studies to detect the full range of brain changes that develop during the gestational period," Dr. Magdalena Martínez García, a postdoctoral researcher in human neuroscience at the Jacobs Lab at UC Santa Barbara, said via email. Martínez García was not involved in the study.
What Brain Changes Mean for Parents
The functional implications of these brain changes for birthing parents have yet to be fully understood, said Dr. Elseline Hoekzema, head of the Pregnancy and the Brain Lab at Amsterdam University Medical Center, via email. Hoekzema was not involved in the study.
However, some of Hoekzema's previous research has suggested that pregnancy-related brain changes may be related to a parent's brain and body responses and bonding with an infant's cues. These findings are also consistent with animal studies indicating brain changes essential for initiating and maintaining maternal care.
The decreases in gray matter volume and cortical thickness could imply that, for the maternal brain, "less might be more," Pawluski said. "It's potentially becoming more efficient."
The increase in white matter microstructure, on the other hand, might suggest "an increase in the exchange of information and communication between different brain areas," Pawluski said. The findings may also have important implications for preventing or treating perinatal mental health issues or supporting a healthy transition to motherhood.
Again, it's essential to keep in mind that these neural shifts observed in one woman may not be common or occur to the same extent in all individuals, so further research involving larger numbers of participants is necessary, experts agree.
The findings so far indicate that these changes in the brain are quite consistent among various women, as Hoekzema pointed out. In one study, all the participants could be categorized as either having been pregnant or not, using a computer algorithm that solely relied on the brain's changes. These alterations have been replicated thus far.
Pawluski aspires for birthing parents to comprehend that these changes are typical and beneficial, rather than perceiving them as a shortcoming associated with the stereotypical understanding of motherhood.
"Our ignorance can have consequences," Jacobs asserted. Until now, researchers lacked the necessary data to anticipate postpartum depression before it surfaced or to decipher the long-term impacts of preeclampsia on brain health.
The study also signifies the commencement of the Maternal Brain Project, an international initiative backed by the Ann S. Bowers Women’s Brain Health Initiative and the Chan Zuckerberg Initiative. A more extensive pool of women and their partners will be incorporated into this project at UC Santa Barbara and Spain for further research.
"We need more data," Jacobs emphasized. Out of the 50,000 brain imaging articles published in the past 30 years, only a minuscule fraction, less than half of 1%, has dealt with health aspects exclusive to women, like pregnancy. Therefore, when we discuss the scientific knowledge base, we need to consider whose physiology it prioritizes.
The study's findings could potentially lead to new approaches to support the mother's brain health during pregnancy, promoting overall wellness and potentially aiding in the prevention or treatment of perinatal mental health issues.
Embracing the knowledge that these neural shifts are common and beneficial for birthing parents can help shift the perception away from viewing these changes as a weakness or shortcoming associated with motherhood, promoting a healthier understanding of the experience.
