It is 2025 and science continues to reveal surprising secrets about the maternal bond. Pregnancy is not just a nine-month period, but an event that leaves permanent traces. The baby's cells, migrating through the placenta from the first weeks, establish themselves in the mother's tissues, from the brain to the heart, creating what scientists call fetal microchimerism. Think about it: physical parts of each child continue to live in you, even decades after birth.
Amy Boddy of the University of California studies how these cells could even protect the mother from certain diseases. It is not just love that binds a mother to her child, it is a deep biological connection that we are only now beginning to understand.
Maternal Bond, the Miracle of Microchimerism
In Greek mythology, the Chimera was a creature with the body and head of a lion, a second goat head on its back, and a snake's tail: different animals mixed in a single body, something so absurd that it became synonymous with impossible. But reality often surpasses fantasy: there really is a form of "chimerism" in the human body, specifically in mothers. During pregnancy, through the placenta, a small number of cells from the baby enter the mother's bloodstream, settling in the tissues.
Cell exchange is bidirectional: the fetus receives cells from the mother (maternal microchimerism) and the mother receives cells from the fetus (fetal microchimerism). This flow is also asymmetric, with a greater number of fetal cells transferred to the mother. The exchange begins as early as the fourth-fifth week of pregnancy, when the woman often does not even know she is pregnant. The real “tattoo” of each pregnancy is invisible to the eye but extremely powerful on a biological level.
These cells live for years
What makes this phenomenon even more extraordinary is its duration: fetal cells do not disappear after birth. According to several studies, can remain in the mother's body for decades, even up to 27 years after birth.
These cells have been found in various maternal organs: lungs, spleen, liver, heart, kidneys and even in the brain.
When the mother's immune system, after birth, "cleans" itself of cells considered foreign, some of these fetal cells manage to escape and integrate into the maternal tissues. They are pluripotent, that is, capable of transforming into various types of cells, and this very characteristic allows them to camouflage themselves and become an integral part of the organs.
Effects on maternal health
But why do these cells persist in the mother's body? The studies conducted by Amy Boddy of the University of California, Santa Barbara, suggest some intriguing hypotheses. One theory is that these cells may have a role in repairing maternal tissue. Fetal cells have been identified at sites of skin inflammation and other damaged areas, suggesting a possible “therapeutic” role.
Research shows that fetal cells may also influence breast milk production, signaling the body when and how much milk to produce during breastfeeding. They are also thought to have a protective role against certain diseases, including certain types of cancer. A Danish study now a decade-long study has even shown a lower mortality rate in women who show fetal microchimerism.
On the other hand, science has also identified possible correlations between fetal microchimerism and some autoimmune diseases. This dualism between protective and potentially harmful effects remains one of the most intriguing aspects of this phenomenon, which requires further research.
Maternal bond, far beyond the emotional bond
The effects of fetal microchimerism go far beyond the physical aspect: may also affect the mother's brain. Some research has found fetal cells concentrated in the hippocampus and the parietal and temporal lobes of the prefrontal cortex, areas associated with comprehension, memory, and perception. This may help explain the deep emotional bond that develops between mother and child.
It's impressive to think that in a study Male DNA found in brain of woman who died at 94, likely evidence of the persistent presence of the child's cells.
This scientific discovery adds a new level of understanding to the mother-child bond, which is not only emotional or psychological, but has deeply biological roots. We no longer simply say “children are part of us” in a metaphorical sense: it is literally true, at a cellular level.
Fetal microchimerism is, therefore, a further confirmation of the uniqueness of the maternal experience and the depth of the bond that is created between a mother and her children. A bond that, as science shows, goes well beyond the nine months of pregnancy, transforming the maternal body forever.
