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Charlotte Lozier Institute

Phone: 202-223-8073
Fax: 571-312-0544

2776 S. Arlington Mill Dr.
#803
Arlington, VA 22206

The
Voyage of Life

Fetal microchimerism

Dive Deeper

Maternal cells transfer to the fetus throughout the pregnancy, including immune cells.1 These cells help to establish and train the child’s immune system2 and, remarkably, can persist to provide cross-generational protection. A child’s grandmother’s cells can be found in his umbilical cord blood!3

When these cells persist, it is called microchimerism; in this case, maternal microchimerism. But the transfer of cells is actually two-way, meaning that the mother also receives cells from the fetus.4 These cells, fetal microchimeric cells, can persist within the mother for decades after the birth of her child! Male cells have been found circulating in mothers whose sons are up to 38 years old.5 6 They can be located in many organs including the heart, where these progenitor cells had matured into functional heart cells.7 It is theorized that these cells from the fetus may participate in regenerating maternal tissue when it is damaged.8

For anyone who has experienced a miscarriage, the discovery that a baby’s cells can remain in a mother’s body for years offers a quiet, tangible reminder that this small life is still present in a real and lasting way. (Image Credit: <a href="https://commons.wikimedia.org/wiki/File:Baby-baby-feet-bed-325690.jpg">Rene Asmussen</a>)
For anyone who has experienced a miscarriage, the discovery that a baby’s cells can remain in a mother’s body for years offers a quiet, tangible reminder that this small life is still present in a real and lasting way. (Image Credit: Rene Asmussen)
Diagram showing Parent 1 transferring maternal and fetal cells (illustrated as colored dots and cells) to two offspring, with Parent 2 shown but not contributing cells. Offspring 1 is orange; Offspring 2 is green.
Microchimerism happens when cells pass between mother and baby during pregnancy. During pregnancy the baby’s cells (represented as orange and green circles) enter the mother’s body, and the mother’s cells enter the baby’s body (represented as purple circles). These cells can stay for years. Sometimes, cells from an older sibling may even be passed to a younger one. (Image Credit: BioEssays)
Back to The Voyage of Life
Sources
  1. ^ Kanaan, S. B., Gammill, H. S., Harrington, W. E., De Rosa, S. C., Stevenson, P. A., Forsyth, A. M., ... & Nelson, J. L. (2017). Maternal microchimerism is prevalent in cord blood in memory T cells and other cell subsets, and persists post-transplant. Oncoimmunology, 6(5), e1311436. https://doi.org/10.1080/2162402X.2017.1311436
  2. ^ Mold, J. E., Michaëlsson, J., Burt, T. D., Muench, M. O., Beckerman, K. P., Busch, M. P., ... & McCune, J. M. (2008). Maternal alloantigens promote the development of tolerogenic fetal regulatory T cells in utero. Science, 322(5907), 1562-1565. https://www.science.org/doi/10.1126/science.1164511
  3. ^ Karlmark, K. R., El Haddad, M., Donato, X. C., Martin, G. V., Bretelle, F., Lesavre, N., ... & Lambert, N. C. (2021). Grandmaternal cells in cord blood. EBioMedicine, 74. https://doi.org/10.1016/j.ebiom.2021.103721
  4. ^ Lo, Y. D., Lau, T. K., Chan, L. Y., Leung, T. N., & Chang, A. M. (2000). Quantitative analysis of the bidirectional fetomaternal transfer of nucleated cells and plasma DNA. Clinical chemistry, 46(9), 1301-1309. https://doi.org/10.1093/clinchem/46.9.1301
  5. ^ Bianchi, D. W., Zickwolf, G. K., Weil, G. J., Sylvester, S., & DeMaria, M. A. (1996). Male fetal progenitor cells persist in maternal blood for as long as 27 years postpartum. Proceedings of the National Academy of Sciences, 93(2), 705-708. https://doi.org/10.1073/pnas.93.2.705
  6. ^ Evans, P. C., Lambert, N., Maloney, S., Furst, D. E., Moore, J. M., & Nelson, J. L. (1999). Long-term fetal microchimerism in peripheral blood mononuclear cell subsets in healthy women and women with scleroderma. Blood, The Journal of the American Society of Hematology, 93(6), 2033-2037. https://doi.org/10.1182/blood.V93.6.2033.406k18_2033_2037
  7. ^ Bayes-Genis, A., Bellosillo, B., de La Calle, O., Salido, M., Roura, S., Ristol, F. S., ... & Cinca, J. (2005). Identification of male cardiomyocytes of extracardiac origin in the hearts of women with male progeny: male fetal cell microchimerism of the heart. The Journal of heart and lung transplantation, 24(12), 2179-2183. https://doi.org/10.1016/j.healun.2005.06.003
  8. ^ Khosrotehrani, K., & Bianchi, D. W. (2005). Multi-lineage potential of fetal cells in maternal tissue: a legacy in reverse. Journal of cell science, 118(8), 1559-1563. https://doi.org/10.1242/jcs.02332
Learn more about Gestational Age

Credentialed scientists reviewed all the material on The Voyage of Life for accuracy. Ages are listed in gestational weeks, measured from the first day of the mother’s last menstrual period, unless otherwise noted. This standard medical practice differs from post-conception age, used by embryologists and medical textbooks cited here, which starts at conception, about two weeks later.

Medical art animation was used to provide a schematic representation of fetal development, with some features, including timing, not to scale. The animation was chosen as an ethically uncompromised guide to fetal development. There are many real human images at each developmental age showing the most accurate fetal forms throughout development. A concerted effort was made to use images and material in which the human embryo or fetus did not undergo any known harm.

Page last updated on May 6, 2026