I wanted to introduce fetomaternal microchimerism and the effect it can have on the mothers body. I want to be able to come to a conclusion on whether or not the cells left behind by the fetus can either benefit or harm the mother.

During pregnancy, so many things happen to both the mother and the child. The mother undergoes many physical changes like weight gain, ligament stretching, and skin darkening. As hormones surge through the mother’s body, they can change her thoughts and feelings. Drastic changes also occur for the baby as each week progresses, and the placenta plays a crucial role. The placenta delivers nutrients and oxygen to the growing baby and processes the waste it creates. The baby receives nutrients from the mother through the placenta, and some of the baby’s cells can cross the placenta and implant into the mother’s organs. 

 Fetomaternal microchimerism (FMc) occurs when a small number of the fetus’s cells cross the placenta and integrate into the mother’s organs. Fetal cell transfer through the placenta is still a relatively new topic and was only discovered in 1893 by “Schmorl, who first identified fetal cells in the lungs of women with eclampsia “(1). Since the discovery of FMc, there has been much debate on whether the cells of a male fetus or the cells of a female fetus cooperate or clash with the mother’s body. Some other studies have suggested that “the transfer of fetal cells carries conflicting interests between males and females, providing them an adaptive and selective advantage” (2). In contrast, some researchers believe that the fetus’s cells cooperate with the mother’s cells by improving health and survival. 

 Fetomaternal cells start to transfer into the mother’s body around the 4th and 6th week of gestation in humans. The number of the fetus’s cells within the mother’s body will continue to increase until the baby is delivered. Most fetomaternal cells left in the mother’s blood circulation will start to disappear, thanks to the mother’s immune system. However, “a small proportion of fetal cells have been found integrated into maternal tissues up to three decades after delivery in humans” (1,2). The fetomaternal cells that managed to elude the mother’s immune system can lay dormant within her tissue, proliferate, or transform the mother’s body. In humans, “the fetal cells, have been found in the mothers skin, spleen, liver, brain, lung, heart, kidney, breast, suprarenal gland, thyroid, lymph nodes, salivary glands, uterus, gallbladder, and intestines” (2). Within these organs, FMc has also been found to be present in certain diseases.    


FMc has been found in many cases of gestational complications, pre-eclampsia, premature births, miscarriages, and different types of cancers(2). While FMc has been found in various cancers and pregnancy complications, it has also been suggested that it benefits the mother. FMc benefits maternal health by participating in tissue repair, regeneration, and cell replacement. FMc has been found in “inflamed maternal tissues, suggesting they are involved in angiogenic and healing processes” (2). FMc has also been found In “lung cancer, primiparous and multiparous women have a better prognosis than nulliparous women and men, suggesting that FMc could suppress maternal tumor development” (2). Studies have also shown that FMc has been related to a lower risk of breast and bladder cancer(2). More testing must be conducted to understand the consequences or benefits of the fetal cells in the mother’s body.  

To better understand how fetal cells might work in the mother’s body, we’ll look at their presents in breast tissue. Some studies have shown that there is a presence of fetomaternal cells within the breast tissue. In one study, more than half the women tested for the presence of fetal cells came back positive for male DNA (3). This shows just how far the fetal cells can travel, but it also begs the question of why they are there. Some researchers suggest that “fetal cells can migrate to the breast and up-regulate milk production either through producing factors that manipulate maternal mammary glands or by differentiating into mammary glands themselves” (3). The cells within the breast tissue could work in the baby’s favor by signaling the baby needs more milk. Again, more research needs to be conducted to understand the full extent of these cells and whether they benefit the mother’s body. 

 I hoped to conclude if Fetomaternal Microchimerism (FMc) is favorable or detrimental to the mother’s body. Unfortunately, since this is still a new subject, most reporting on this topic is where the fetomaternal cells have been found in the mother.

I drew an image of the fetal microchimerism cells going through the placenta and into the mothers various tissues. 

Fetomaternal and Materno Fetal Microchimerism

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3084951/
  1. https://www.sciencedirect.com/science/article/pii/S2589004221016345
  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4712643/ 
  1. https://academic.oup.com/clinchem/article/67/2/351/6071463 
  1. https://harvardsciencereview.org/2015/12/04/fetal-microchimerism-2/ 


  1. Great work! I loved your image. While it was simple it explained the mechanism of action very well, and was clear to the viewer the message you were conveying! Your level of detail within the paper was fantastic and I learned a ton about fetomaternal microchimerism. This is not something I had ever heard of before and you really made me feel like I had a deep understanding about it by the end of the comment and after viewing your image in detail. I found it incredible how long these fetal cells can stay in the body after delivery THREE DECADES! I found this fascinating as the body is so good at getting rid of things in general! I also found it interesting how some have been correlated to complications and some to benefits. I wonder if the ones that do stick around for so long are selected to stay by the immune system because they are correlated to benefits within the body? It was awesome reviewing your project cause it kind of tied into mine when you talked about milk production! I found it very interesting that this could help signal for milk production as my whole project was on how mothers that struggle breastfeeding due to milk shortages could increase milk supply. Your project’s drawing was simple, beautiful, and informative! Great work!

  2. This project described fetomaternal microchimerism. She described the benefits and cons to fetuses microchimerism going into the mothers system and tissues. She also described how long these are present within the body and where they are most commonly found within the body after delivery. She showed.a beautiful image of the mechanism of action for this and described how these mirochimerism cells can even improve milk production!

    Adryahn Bodyfelt

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