Charlie Camosy interviews Kristin Marguerite Collier, Assistant Professor of Internal Medicine at the University of Michigan Medical School, on the relationship between a mother and a child prior to the child’s birth. Kristin Collier writes:

As many of your readers may know, the placenta is the organ through which the mother and prenatal child interface. The placenta is an organ that is attached to the inside of the uterus and connects to the prenatal child through the child’s umbilical cord.

What is not as well known about this organ is that the placenta is the only organ in human biology that is made by two persons, together, in cooperation. The placenta is ‘built’ from tissue that is part from mom, and part from the growing baby. Because of this, the placenta is referred to as a ‘feto-maternal’ organ. It is the only organ made by two people, in cooperation with providence. It is the first time mom and her baby come together, albeit at the cellular level, to do something in cooperation.

Whenever I think of this, I picture the ceiling of the Sistine Chapel, where Michelangelo depicts God and Man reaching out for one another, hands about to touch and perhaps entwine. In the creation of the placenta, cells from the trophoblast, which are from the embryo, ‘reach down’ towards the mother’s uterine wall while at the same time, the spiral arteries from the mother’s uterus are ‘reaching’ up towards the embryo. This process leads to the creation of the placenta.

The placenta is the only purposely transient organ in humans and unlike the rest of our organs, acts as many organs in one. The placenta functions to eliminate waste, like the kidneys would do, facilitates transfer of oxygen and carbon dioxide, like the lungs would do, and provides nutrients, like a GI tract would do. It even has endocrine and immune function. What used to be discarded as just the ‘afterbirth’ is now regarded as a magnificently complex shared organ that supports the formation of the prenatal child.

The placenta is such an important organ that the National Institutes of Health (NIH) has established, under its “Eunice Kennedy Shriver National Institute of Child Health and Human Development” arm, the “Human Placenta Project” (HPP). The website says “The placenta is arguably one of the most important organs in the body. It influences not just the health of a woman and her fetus during pregnancy, but also the lifelong health of both mother and child.” The aim of the HPP is to better understand, through research, the amazing placenta with the ultimate goal of improving the health of children and mothers. The research done by the HPP continues to demonstrate that a child’s prenatal and postnatal health is inextricably linked to the health of the placenta.

In addition to the placenta, mother and prenatal child interact at a cellular level in something known as ‘fetomaternal microchimerism’. In Greek Mythology, the chimera is a fire breathing monster comprised of three species in one – a lion’s head, a goat’s body and a serpent’s tail. In science, “microchimerism” is the presence of a small population of genetically distinct and separately derived cells within an individual. During pregnancy, small numbers of cells traffic across the placenta. Some of the prenatal child’s cells cross into the mother, and some cells from the mother cross into the prenatal child. The cells from the prenatal child are pluripotent and integrate into tissues in her mother’s body and start functioning like the cells around them. This integration is known as ‘feto-maternal microchimerism’.

The presence of these cells is amazing for several reasons. One is that these cells have been found in various maternal organs and tissues such as the brain, the breast, the thyroid and the skin. These are all organs which in some way are important for the health of both the baby and her mother in relationship. The post-partum phase is when there is need, for example, for lactation. The fetomaternal microchimeric cells have been shown to be important in signaling lactation. These cells have been found in the skin, for example, in Cesarean section incisions where they are helping to produce collagen. Baby is helping mom heal after delivery by the presence of her cells! It would be one thing for these cells to come into the mother and be inert, but is a whole other thing entirely that these cells are active and aid mom for example in helping to produce milk for her baby and helping her heal. These cells may even affect how soon the mother can get pregnant again and therefore can affect spacing of future siblings.

Usually, foreign or ‘other’ cells are detected by the host immune system and are destroyed. The fact that these fetal cells ‘survive’ and then are allowed to integrate into maternal tissue speaks to a ‘cooperation’ between the mother and her child at the level of the cell that parallels that seen in the development of the placenta, suggesting that the physical connection between mom and baby is even deeper and more beautiful than previously thought. Research in fetomaternal microchimerism suggests that the presence of these cells may favorably affect the future risk of malignancy. The presence of these cells in the maternal breast may help protect mom from breast cancer years after the baby’s birth.

To think that a physical presence of the baby in her mother is helping protect her from cancer at the level of the cell, speaks to a radical mutuality at the cellular level that we are just beginning to understand. Some of the effects of fetomaternal microchimerism, however, may be detrimental in some cases. This research is still underway. The big takeaway is that the science of microchimerism supports the fact that some human beings carry remnants of other humans in their bodies. Thus, we aren’t the singular-autonomous individuals we think of ourselves as being.

And Michael Pakaluk writes along the same lines, reflecting on the theological implications of our contemporary understanding of pregnancy:

“Mothers around the world say they feel like their children are still a part of them long after they’ve given birth,” said a recent Smithsonian Magazine article, “As it turns out, that is literally true. During pregnancy, cells from the fetus cross the placenta and enter the mother’s body, where they can become part of her tissues.”

It works the other way, too.  Cells from the mother also cross the barrier.  But these cells are not “pluripotent”; their life spans and possible influences are short-lived.

Evolutionary biologists are fascinated by the exchange, because they view it as a symbiosis that contributes to the “fitness” of both mother and child.  Preliminary evidence suggests that fetal cells may stimulate milk production, help wounds to heal, and strengthen the mother’s immune system. …

But let’s think of Mary’s pregnancy in this way.  Jesus was “perfect God and perfect man,” like us in all ways except sin. Therefore, let us suppose that cells from the unborn Jesus migrated into Mary’s blood and lodged in various organs, where they took on the functions of those organs, and remained until Mary was assumed into Heaven. They were not Mary’s cells, but the cells of the Lord, alive within Mary’s body and playing the same function as Mary’s cells. …