During pregnancy, cells of the foetus often migrate through the placenta, taking up residence in many areas of the mother's body, where their influence may benefit or undermine maternal health, a research has found.
These foetal cells which can persist in maternal tissues for decades after a child is born — have been associated with both protection and increased susceptibility to a range of afflictions, including cancer and autoimmune diseases like rheumatoid arthritis, the study said.
"Foetal cells can act as stem cells and develop into epithelial cells, specialised heart cells, liver cells and so forth," said study lead author Amy Boddy, researcher at Arizona State University in the US.
"This shows they are very dynamic and play a huge role in the maternal body. They can even migrate to the brain and differentiate into neurons," Boddy said.
The presence of foetal cells in maternal tissue is known as fetal microchimerism.
The researchers reviewed the available literature on foetal microchimerism and human health, and found that foetal cells enter a cooperative relationship in some maternal tissues, compete for resources in other tissues and may exist as neutral entities — hitchhikers simply along for the ride.
It is likely that foetal cells play each of these roles at various times, the study said.
For example, foetal cells may contribute to inflammatory responses and autoimmunity in the mother, when they are recognised as foreign entities by the maternal immune system.
This may account in part for higher rates of autoimmunity in women.
Foetal cells can also provide benefits to mothers, migrating to damaged tissue and repairing it.
In other cases, foetal cells from the placenta are swept through the bloodstream into areas including the lung, where they may persist merely as bystanders.
The findings appeared online in the journal Bioessays.