How pregnancy creates a biological connection that can last decades
From hearing a baby’s heartbeat for the first time to feeling those early kicks, pregnancy is often described as one of the most profound experiences in a woman’s life. Beyond the emotional connection, science reveals that pregnancy also creates a lasting biological bond between a mother and her child — through a phenomenon known as microchimerism.
What Is Microchimerism?
Microchimerism refers to the presence of a small number of cells in one individual that originate from another individual. This usually occurs between a mother and her fetus during pregnancy.
In fetal microchimerism, cells from the fetus cross the placenta and enter the mother’s bloodstream. These fetal cells can settle in organs such as the:
- Thyroid
- Liver
- Lungs
- Heart
- Brain
Conversely, maternal microchimerism occurs when cells from the mother enter the fetus. Remarkably, these maternal cells can persist and may even be passed on to future generations.
Microchimerism Can Last a Lifetime
According to a study published in Advanced Sciences in August last year, microchimeric cells can remain in the body for decades — potentially for life.
“Fetal microchimerism refers to cell transfer from the fetus to mother. Maternal microchimerism describes maternal cells that are transferred to the offspring. Microchimerism can also arise from twinning, as well as organ and stem cell transplantation,” the researchers wrote.
The study also found that these cells are highly adaptable. Both fetal- and maternal-derived microchimeric cells can:
- Differentiate into nearly any cell type
- Colonise almost any tissue
- Cross the blood-brain barrier and even develop into neurons
How These Cells May Affect Health
Experts say microchimeric cells can play both protective and harmful roles.
On the positive side, these cells may:
- Contribute to tissue repair and regeneration
- Differentiate into cardiac, endothelial, and immune cells
- Support healing processes within the body
However, microchimerism has also been associated with:
- Autoimmune diseases
- Pregnancy-related complications
- Certain chronic health conditions
Scientists are still investigating whether these cells directly cause disease or appear in greater numbers as part of the body’s natural response to injury.
What Experts Say
In a separate study published in Immunity, infectious disease specialist Sing Sing Way from Cincinnati Children’s Hospital Medical Center highlighted the importance of understanding how foreign maternal cells interact with the immune system.
“The new tools we developed to study these cells will help scientists pinpoint exactly what these cells do and how they work in a variety of contexts including autoimmune disease, cancer and neurological disorders,” Way said, as quoted by Science Alert.
He added that microchimerism is increasingly linked to multiple health conditions, but more research is needed to determine its precise role.
“This study provides an adaptable platform for scientists to investigate whether these rare cells are the cause of disease, or alternatively, found in diseased tissue at increased levels as part of the natural healing process.”
A Bond That Goes Beyond Birth
Microchimerism highlights how pregnancy creates a deep, biological connection that extends well beyond childbirth. While science is still uncovering its full implications, the phenomenon offers a powerful reminder that a mother and child may remain linked — cell by cell — for a lifetime.