This post is written especially in mind for anyone that has had a successful pregnancy or suffered fertility struggles, the loss of a foetus through miscarriage or abortion, the trauma of a stillborn baby, or the devastation of the loss of a child.
If you’re female, what if you discovered that it’s quite possible you aren’t who you thought you were and maybe you aren’t entirely controlling yourself? Freaked out? Interested to know what I mean? Then read on. If you’re male with a female partner, at this point you might already be thinking that this makes a lot of sense, full stop. But still, read on!
For many prospective parents, the journey to a healthy baby in your arms is a long and often stressful one. With the average age of first-time mothers (and fathers) creeping ever higher, so too are fertility issues. It can be months or years before conception is successful and even then so many mothers experience the distress and devastation of miscarriage and fewer but not insignificant numbers also experience the mind-numbing shock of a stillborn baby. Women engaging in sexual intercourse without contraception most likely have experienced miscarriages, with about half of all fertilized eggs dying and then being lost (aborted) spontaneously, typically before the woman knows she is pregnant. The miscarriage rate is about 20% among women who know they are pregnant.
The former happened to me, the first month we started trying for a baby. I clearly felt fertilisation take place and then the movement of the fertilised egg down my fallopian tube and the very beginning of implantation. It was incredible to be that connected with my body, to feel the beginnings of life. Then though, my body went silent; everything suddenly felt wrong and I started bleeding. I couldn’t in any way prove my story but I know it’s true- women when they tune in can have very good insight into the inner workings of their body (this is the focus of an upcoming post). And even though it was just a ball of cells I felt a brief but intense flood of grief over the weekend that followed. This ball of cells felt like it had so much potential. Most likely, though implantation was not successful because something hadn’t gone to plan and this was a quality control measure to protect resources. Eventually my head accepted this idea.
Many women I know though have experienced that second category of miscarriage (or even stillbirth) when miscarriage occurs after they know they are pregnant. In this situation, the grief and sense of loss can be far longer lasting and have profound effects on the wellbeing of the woman and her partner.
What then does this have to do with not being who you thought you were? The excellent and very informed Dr Alison Barrett, obstetrician @DrAlisonBarrett alerted me to the information I am about to share at the New Zealand La Leche League conference where she spoke last year.
It turns out all mothers (and even those that have suffered miscarriages post implantation but never carried a baby to term) most likely have fetal cells living and residing in their tissues, and incredibly for decades. Although it was previously known that fetal cells circulate in mother’s blood a 2012 study by Nelson et al, showed that DNA from male cells (most likely from a foetus, but possibly from a sibling) is frequently found (more than 60%) throughout deceased women’s brains (and other tissues). This is called microchimerism, where there is a persistent presence of a few genetically distinct cells within another organism. Note that it’s easy to identify male DNA (i.e. the Y chromosome, which is found only in males) in female subjects, which is why the study focused on the presence of male DNA. Female foetuses will in all likelihood also pass cells to their mother via the same mechanism.
For my early implantation failure, it is unlikely but not impossible any of that ball of cells made its way further into my body and now live on. The route is most likely via the placenta (organ connecting mother to foetus that is the means of exchange of nutrients, gas and waste), after it forms after implantation. The fetal cells it turns out are capable of breaking through the blood-brain barrier, to reside in the brain. They also end up in other tissues such as lung, thyroid muscle, liver, heart, kidney and skin, where they can fuse with cells the mother has to form chimeric cell lines, which is a pretty weird concept when you think about it.
Even more eerily microchimerism has other forms as well. Foetuses can also pick up cells from a twin, or even an older sibling, as some fetal cells do linger on in the uterus. In a truly heartbreaking story, a mother nearly lost her children through trying to prove they were hers for custody and failing- they had none of her DNA and must have arisen from ovarian tissue from her unborn twin- “she was her own twin – and the twin was the biological mother of her children”. Microchimerism can even occur following blood transfusions in immunocompromised patients. So rather than us being just us, we are not the autonomous beings we thought.
It is bizarre to consider that we carry fragments of others and even stranger when we consider we are used to thinking of our mind as our own. Now though, we know that within our brains we have cells from others living and functioning and influencing how we function in ways we don’t yet understand.
There are potential health implications of having fetal microchimeric cells residing within us. They are likely to play a role potentially in protecting us from disease, tissue repair and cancer prevention and they may be involved in immune disorders. The Nelson study for example, found lower amounts of microchimeric cells in women with Alzheimer’s. And in rats it has been found that if a pregnant rat was artificially given a heart attack that fetal cells migrate selectively to the injured heart tissue and help repair it. Now that is totally incredible! Baby helps mum even before the baby is born. I will expand on what the studies show in a later post.
For me, when I first heard this information I was blown away: blown away because it is conceptually so interesting and seemingly like farfetched science fiction, but also aware that this should be public knowledge for all women. Many women grieve for a baby they lost at some point. To comfort, people often talk about the (angel) baby looking down on them from heaven. However, I think a far more comforting thought is knowing that living pieces of your child are inside you, never leaving your body.
I hope that this really does give solace to those that have experienced this kind of loss. You carry your child with you for life.
And for those of us lucky enough to have children that we conceived and gave birth to, I think it’s also incredibly comforting to know that for the duration of our lives, little pieces of our children also live on in us.
My theory, based on the current evidence, is that the role of these fetal cells is to provide protection to the mother, in order that she is around to care for her child until adulthood and beyond. And isn’t that perhaps the greatest gift perhaps our children may give us? Aside from the way they also visibly enrich our lives on the outside. Could this be part of a mechanism too for how ‘memories’ pass between generations? The human body is really remarkable even now we know the human body is really a humans body.
This is a post in an episodic series I will put out on the wonders of being a micro-chimaera, the incredible world of epigenetics and what it all may mean for parents. Subsequent posts in this series will look in more detail at: 1) these microchimeric fetal cells within mothers and what the science tells us their role might be; 2) the flipside- maternal cells that migrate to the fetus pre- and post-birth and what their role may be; and 3) what epigenetics is and why parents might be interested in it.
 Dawe et al 2007. Cell Migration from Baby to Mother Cell Adh Migr. 1(1): 19–27. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633676/
 Chan et al 2012. Male Microchimerism in the Human Female Brain. PLOSOne 7(9): e45592 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0045592
 Kara et al 2012. A Mouse Model for Fetal Maternal Stem Cell Transfer during Ischemic Cardiac Injury. Clin. Trans. Res. 5:321-328. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3419501/
 Kara et al 2012. Fetal Cells Traffic to Injured Maternal Myocardium and Undergo Cardiac Differentiation. Circ. Res. 110:82-93. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3365532/