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RACHEDI A. (JSBB), Volume 4, Issue 2, August 2025

ISSN 2830-8832

Journal Concepts in Structural Biology & Bioinformatics

GENOMICS-PROTEOMICS

Concept article – Scientific Commentary

Fetal Microchimerism and Motherhood: Biological

Memory Beyond Pregnancy

RACHEDI Abdelkrim^*

1

Laboratory of Biotoxicology, Pharmacognosy and biological valorisation of plants, Faculty of Natural & Life Sciences,

Department of Biology, University of Saida Dr. Moulay Tahar, Saida, Algeria.

*Correspondence: abdelkrim.rachedi@univ-saida.dz

Published: 15 August 2025

Abstract

Pregnancy is traditionally understood as a temporary physiological state during which the mother supports the

growth of a genetically distinct fetus. However, accumulating evidence demonstrates that pregnancy leaves a

lasting cellular legacy in the maternal body. Fetal cells can migrate into maternal tissues, persist for decades, and

in some cases differentiate into specialized cell types. This phenomenon, known as fetal microchimerism,

challenges classical notions of genetic individuality and opens new perspectives on maternal health, immunity, and

disease susceptibility. This commentary reviews current scientific knowledge, highlights established findings, and

critically examines emerging hypotheses.

Keywords: Pregnancy; Fetal Microchimerism; Genetics; Immunity

1. Fetal–Maternal Cell Exchange: A Persistent Biological Connection

During normal pregnancy, cells cross the placental barrier in both directions. While maternal cells entering

the fetus were recognized early, the long-term persistence of fetal cells in the mother was only clearly

demonstrated in the late 20th century.

Fetal cells have been detected decades after childbirth in maternal blood, skin, liver, lung, thyroid, and

brain tissue. Male fetal cells, identified by Y-chromosome markers, have provided particularly compelling

evidence of long-term persistence, Figure 1.

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Figure 1. Illustration of cell transfer across generations; Cells are exchanged between

the proband's mother (orange) and the proband (yellow) in utero. Maternal

microchimerism persists in the proband into adulthood. During pregnancy, the

proband acquires fetal microchimerism (green). Simultaneously, the fetus acquires

maternal microchimerism (yellow), (Jacobsen et al., 2025).

2. Stem Cell–Like Properties of Fetal Cells

Many fetal microchimeric cells exhibit characteristics consistent with stem or progenitor cells, including

the ability to proliferate and differentiate. In animal models, fetal cells have been shown to adopt phenotypes

consistent with hepatocytes, cardiomyocytes, epithelial cells, and neurons.

In maternal brain tissue, fetal-derived cells expressing neuronal and glial markers have been identified,

suggesting potential integration into neural environments.

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3. Potential Role in Maternal Tissue Repair

One of the most compelling hypotheses is that fetal microchimeric cells may participate in tissue repair

and regeneration. Observational studies suggest correlations between the presence of fetal cells and

improved outcomes in certain conditions.

For example:



Lower levels of fetal microchimerism have been reported in women with Alzheimer’s disease

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Similar observations exist for breast cancer, although findings are not uniform

4. Immunological Tolerance and Surveillance

Fetal cells are semi-allogeneic, carrying paternal antigens foreign to the maternal immune system.

Remarkably, these cells are often tolerated rather than eliminated.

This tolerance may:



Reflect immune adaptations established during pregnancy

Influence long-term immune surveillance mechanisms

Some authors propose that persistent exposure to genetically distinct fetal cells may enhance maternal

immune responsiveness against tumor cells, which also display altered genetic signatures.

5. Microchimerism Beyond Mother and Child

Cellular exchange may extend beyond a single pregnancy:



Cells from older siblings may be transferred via the mother

Maternal cells from a grandmother may persist across generations

In identical twins, bidirectional cell exchange can occur in utero

These findings complicate classical definitions of biological individuality and heredity.

6. Plastic-Degrading Bacteria and Enzymes

Fetal microchimerism forces

a

reassessment of the idea that an individual is genetically

autonomous. Instead, humans may be viewed as cellular mosaics, shaped by pregnancy history

and familial lineage.

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For students of biology and medicine, this phenomenon exemplifies:



The plasticity of biological systems

The limits of reductionist genetic definitions

The deep integration of reproduction, immunity, and long-term health.

7. Scientific Caution and Future Directions

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While fetal microchimerism is an established biological reality, clinical applications remain

premature. Key unresolved questions include:



Are fetal cells functionally integrated or merely present?

Under what conditions are they beneficial versus pathogenic?

Can they be safely harnessed for regenerative medicine?

Rigorous longitudinal studies and mechanistic experiments are required before translation into

therapy.

Conclusion

Fetal microchimerism represents one of the most striking examples of long-term biological

interaction between individuals. It enriches our understanding of motherhood not as a transient

state, but as a permanent biological transformation. At the same time, it reminds us of the

necessity of scientific rigor: fascination must be balanced by critical evaluation.

References

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 of the United States of America, 93(2), 705–708. https://doi.org/10.1073/pnas.93.2.705

Boddy, A. M., Fortunato, A., Wilson Sayres, M., & Aktipis, A. (2015). Fetal microchimerism and maternal

health: a review and evolutionary analysis of cooperation and conflict beyond the womb. BioEssays : news

and reviews in molecular, cellular and developmental biology, 37(10), 1106–1118.

https://doi.org/10.1002/bies.201500059

Jacobsen, D.P., Fjeldstad, H.E., Olsen, M.B., Sugulle, M., Staff, A.C. (2025). Microchimerism and pregnancy

complications with placental dysfunction. Seminars in Immunopathology, 47(21),

https://doi.org/10.1007/s00281-025-01045-w

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Lambert, N., & Nelson, J. L. (2003). Microchimerism in autoimmune disease: more questions than

answers?. Autoimmunity reviews, 2(3), 133–139. https://doi.org/10.1016/s1568-9972(02)00149-0

Gadi, V. K., & Nelson, J. L. (2007). Fetal microchimerism in women with breast cancer. Cancer

research, 67(19), 9035–9038. https://doi.org/10.1158/0008-5472.CAN-06-4209

Khosrotehrani, K., Johnson, K. L., Lau, J., Dupuy, A., Cha, D. H., & Bianchi, D. W. (2003). The influence of

fetal loss on the presence of fetal cell microchimerism: a systematic review. Arthritis and

rheumatism, 48(11), 3237–3241. https://doi.org/10.1002/art.11324

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Martone, R. (2012, December). Scientists Discover Children’s Cells Living in Mothers’ Brains. Scientific

American: https://www.scientificamerican.com/article/scientists-discover-childrens-cells-living-in-

mothers-brain/

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