Mothers Carry Pieces of their Children—In Their Brain

Did you know that long after you’re born, your mother carries little parts of you in her body? This phenomenon is called ‘microchimerism’, the presence of foreign cells in a tissue or organ. Recent research has now found cells from the foetus in the most distal part of the mother’s body, the head.

Babies’ Cells Migrate Into Mothers’ Bodies

Microchimerism arises during pregnancy when fetal cells move into the mother’s body where they may persist and multiply for a long time. This phenomenon is how the complete sequence of a foetus’s DNA can be determined simply from the mother’s blood. The effects of these cells on the mother’s health, if any, aren’t known. Some hypothesize that these ‘foreign’ cells could trigger off the mother’s immune system leading to autoimmune diseases. Others hypothesize that these cells actually help in the repair of damaged tissues in the maternal body. The kidneys, lungs, liver, lymph nodes and the hearts of mothers have been found to contain their sons’ DNA. Do they also travel to the brain?

fetal DNA in mother's brain
The origins of microchimerism. It is during pregnancy that cells from the foetus enter the mother’s body and may persist for as long as a few decades. [Image Credit: Wikimedia commons]

Looking for Y Chromosomes in Female Brains

Firstly, let’s talk about why ‘son’s’ DNA is mentioned, but not daughters’ DNA lest scientists be accused of sexism. Males contain a copy of the Y chromosome while females don’t. Merely finding a piece of this chromosome in a woman would be sufficient to determine the presence of foreign cells (most likely to be her son’s). On the other hand, to look for a daughter’s DNA, scientist would have to look for very specific differences between the mother and the daughter’s genes.

Keeping this in mind, researchers at the University of Washington in Seattle tested if a particular sequence of DNA in the Y chromosome was found in the brains of women who had sons. 63% of mothers were found to contain this segment of DNA, indicating that fetal cells do, in fact, travel all the way to the brain.

The next time your mother says you’re in her heart or on her mind, you know she means it literally. You can read about this research here.

Published by

Shweta Ramdas

Beginning life as a grad student studying human genetics.