You’ve probably seen those health “did you know?” videos on TikTok. Here’s a shocking fact for moms: Did you know, a child’s DNA can linger in your body for years after childbirth?
And if you’re the firstborn, a bit of you may always be with your mother. It sounds like science fiction, doesn’t it? Yet, it’s a real phenomenon, and it’s got scientists rethinking everything from autoimmunity to cancer.
@museumofscience Did you know that your DNA might have hung around in your biological mother’s body for up to 27 years after you were born? @Alex Dainis 🧬🔬 explores the incredible phenomenon of fetal microchimerism and how your DNA can affect maternal health. #GeneticsTikTok #DNA #MomTok #Genetics #Pregnancy ♬ original sound – Museum of Science
What is microchimerism?
The name sounds intimidating, but it’s fascinating. “Micro” means small, and “chimaera” comes from Greek mythology, a creature made of different animals. In biology, microchimerism describes having a tiny amount of someone else’s DNA inside you.
In this case, it’s your child’s. During pregnancy, some of your baby’s cells slip across the placenta and settle in your body. These cells can stay there for decades, quietly mingling with your own tissues.
Scientists have found that mothers can carry DNA from each of their children, sometimes even from pregnancies that didn’t go to full term.
How long do these cells last?
Research from the National Health Institute confirms that cells from your firstborn (and any other children you have) can remain in your body for years, even decades. And yes, even if a pregnancy doesn’t go to full term, some of those fetal cells can still stay behind.
These cells aren’t just passive stowaways; many are pluripotent, like stem cells, meaning they can transform into different types of tissue. They migrate, settle, and even help repair damage, blending in with your heart, liver, brain, and more.
Why does this happen?
It’s a story millions of years in the making. According to Dr Amy Boddy, a geneticist at Arizona State University, this strange exchange between mother and child likely evolved as a kind of biological negotiation.
The fetus tries to draw as many resources as possible, while the mother’s body balances giving and protecting herself (Boddy et al., 2015). But the real twist? These leftover baby cells may affect your health long after pregnancy.
@tiktokamirr My little sister is my son fr 😂 #firstborn #firstbornchild #theoldestsibling #joselinehernandez #sibilinggoals ♬ Joselineeee hernandezzzz – BlkKendoll
The surprising impact on health
Scientists are only beginning to understand what these microchimeric cells do. The evidence is both exciting and a little unnerving:
Cancer: Some research hints that fetal cells might help repair damaged tissues and even fight cancer. Interestingly, they’ve also been found in tumour tissues, raising the possibility that they sometimes fuel cancer development (American Association of Pharmaceutical Scientists, 2018).
Autoimmune disease: Studies show that pregnancy can protect women from arthritis for years, possibly because of these fetal cells.
Immune memory: Microchimerism doesn’t just go one way. Maternal cells can also pass into the baby, shaping the immune system even after birth. This could help explain why some children have stronger or weaker immune responses (National Institutes of Health, 2021).
What does this mean for you?
According to the baby blog “Cradlewise”, if you’re a mother, you’re quite literally carrying pieces of your children with you.
It’s a powerful thought, one that makes the “my kids are always a part of me” saying feel a lot more real. And if you’re a firstborn or have siblings, your DNA might be mingling inside your mom right now.
