It is often said that mothers have a certain “maternal instinct” and how magical the bond is that mother and child(ren) share. While we all agree that this mother-child born happens naturally, there is an actual scientific explanation for why maternal instincts exists and it boils down to cells.

Of course, it’s not quite as simple and what happens is that during pregnancy, some of the foetus’ cells cross over from the placenta into the mother’s body. This process is called microchimerism and normally, the foetus’ cells which crosses over are ‘cleaned’ up by the mother’s body once the baby is born but they often remain in the mother’s body, eventually becoming part of the mother’s body.

This phenomenon isn’t so weird among mammals; in fact, it’s been around since the first placental mammals roamed the earth. It was first discovered in humans several decades ago when a DNA report showed male cells inside of a woman’s bloodstream. The discovery caused an uproar, but they were unable to make further research due to a lack of technology at the time.

All of that has changed now. Thanks to deep-sequencing, researchers can go through a person’s DNA by exploring their genomes individually, allowing them to take a closer look at each gene that makes them.

Genes associated with immunity stand out in particular as they are unique to every person, thus making it easier to figure out who they belongs to.

However, this hasn’t stopped scientists’, such as Dr Amy Boddy and her team, curiosity in wanting to know why microchrimerism happens and how it can affect women who give birth.

Boddy explains that the reason for microchimerism comes when foetal cells from the baby can cross the placenta and enter the mother’s bloodstream. These foetal cells act like stem cells and are thus able to take on shelter among other tissues and can even take up that fabric’s form with the help of chemical cues. However, it’s still hard to tell why these processes happen in the first place.

There have been many effects listed when it comes to microchimerism. For example, a study on mice showed how foetal cells lodged in mammary glands can help improve the flow and quality of breast milk or how they can assist the mother’s healing mechanism.

There are still many aspects of it that biologists want to investigate, however, chief among them how a mother who has undergone multiple pregnancies can be affected and how it affects the babies as well.

David Haig, an evolutionary biologist at Harvard University talks of the possibility that foetal cells from past pregnancies could influence the rate in which a mother can get pregnant again, they could even hinder other babies’ growth or delay their birth.

That’s not all, while some good things come out of microchimerism, scientists have also noted the adverse effects that can come from it. Chief among them is the fact that foetal cells can act in a similar way to cancer cells, meaning that they can increase the likelihood of developing some form of cancer.

Scientists are also trying to figure out exactly where foetal cells allocate once they enter the body. Scientists believe that aside from the breasts, these foetal cells can also enter the thyroid, which will then affect metabolism and thus, transfer more heat to the baby and the brain, which could potentially influence the attachment that a mother has to her children.

That is probably why a lot of mothers say that they often feel like their children are still part of them even after having given birth!

While all this is still in the midst of medical research, what does not change is how amazing pregnancy and motherhood are. We are grateful and thankful to all mothers and would once more like to wish them a Happy Mothers’ Day!

Photo Credits: Babble, Safety Kart, Forbes

Reference: Smithsonian