From Child to Mother: Fetal Cells in Maternal Tissue May Impact Maternal Health After Childbirth

Most of us probably know that the mother’s health is important for the well-being of their developing fetus. However, a recent study published in BioEssays suggests that the fetus may also affect the health of its mother — even after the pregnancy is over. The study showed that fetal cells migrate from the placenta and reside in several parts of the mother’s body, where they may exert benefits (such as improved milk production and thermoregulation), harms (such as autoimmune diseases and cancer), or have no effect (such as their presence in the lung).

Although this fetal microchimerism (the presence of fetal cells in maternal tissue) has been known to exist in humans and other placental mammals, its impact on maternal health has not been elucidated. Researchers in the Arizona State University’s Department of Psychology reviewed existing data on fetal microchimerism and maternal health and applied an evolutionary framework to predict when fetal cells enhance maternal health and when they contribute to adverse effects. The data suggest fetal cells enhance breast development and lactation, as poor lactation is linked to low fetal cell count in breast tissue. Fetal cells may also migrate to and repair damaged tissue, and their presence at wound sites (including caesarian incisions) suggests their active role in healing.

Fetal cells have also been found in the thyroid gland, where they may enhance heat transfer to the fetus. Women with thyroid diseases tended to have high levels of fetal cells in blood and thyroid tissue, possibly due to the maternal immune system attempting to obtain control from the influence of fetal cells. Furthermore, women with breast cancer tend to have a lower abundance of fetal cells in their breast tissue than do healthy women, suggesting the cells are protective against breast cancer. However, other data suggest the fetal cells are linked to a transient increase in breast cancer risk in the years immediately following pregnancy.

Although these preliminary findings introduce intriguing hypotheses for maternal health and disease, much research is necessary to fully understand the impact of the fetal microchimerism, which is complex. For example, the mother’s cells have also been shown to cross back through the placenta, and cells from fetuses in subsequent pregnancies may cross the placenta and enter the microchimeric arena to introduce “sibling rivalries” in the mother’s tissues. Nevertheless, the researchers suggest fetal cells could play a role in therapeutic approaches for conditions such as poor lactation and wound healing.

Source: Boddy AM, et al. (2015) Fetal microchimerism and maternal health: A review and evolutionary analysis of cooperation and conflict beyond the womb. BioEssays.