Maternal-Fetal Immune Interactions During Pregnancy

Pregnancy represents a unique immunological state in which the maternal immune system must achieve a delicate balance between tolerance of the semi-allogeneic fetus and defence against pathogens. Central to this balance is the maternal–fetal interface, where specialised maternal immune cells in the decidua interact with foetal trophoblasts to modulate immune responses. Uterine natural killer (uNK) cells, macrophages and antigen-presenting cells contribute to vascular remodelling, trophoblast invasion and local immune regulation. Regulatory T cells accumulate in the decidua to suppress potentially harmful T-cell responses against foetal antigens, while tissue-resident memory T cells maintain local surveillance without provoking rejection. Systemic adaptations in the maternal immune compartment—including shifts in peripheral T-cell subsets and the generation of foetal antigen-specific memory cells—further support gestational immune tolerance. Emerging evidence also highlights the role of placental-derived extracellular vesicles and microchimerism in educating maternal immunity. Disruption of these finely tuned interactions is implicated in pregnancy complications such as pre-eclampsia, recurrent miscarriage and preterm labour, underscoring the global significance of understanding maternal–fetal immunology for maternal and child health.

Research from Nature Portfolio

Human uterine lymphocytes acquire a more experienced and tolerogenic phenotype during pregnancy, revealing that endometrial lymphocytes transition into decidual populations enriched for central and effector memory T cells and regulatory T cells. This shift reflects a pre-pregnancy ‘priming’ of uterine immunity and offers a minimally invasive source for studying immune dysfunction in pregnancy complications. An analysis of endometrial tissue in women with recurrent miscarriage uncovered a marked reduction in tissue-resident CD8+ memory T cells expressing CD69 and CD103, indicating that altered memory cell residency and homeostatic signalling may underlie unexplained pregnancy loss. These findings suggest that stable imprints in endometrial immunity influence subsequent pregnancy outcomes and may guide diagnostic and therapeutic strategies for recurrent miscarriage.

Maternal-Fetal Immune Interactions During Pregnancy publication trend

The graph below shows the total number of articles in maternal-fetal immune interactions during pregnancy across all publications each year (not limited to Nature Index journals).

Technical terms

Decidua: The specialised endometrial lining of the uterus during pregnancy, rich in maternal immune cells and stromal elements.

Trophoblast: Foetal cells that invade the decidua and form the outer layer of the placenta, mediating nutrient exchange and immunomodulation.

Regulatory T cell (Treg): A subset of CD4+ T cells that suppress immune activation and maintain tolerance to self and foetal antigens.

Tissue-resident memory T cell (Trm): A long-lived T-cell subset that resides in non-lymphoid tissues, providing local immune surveillance without recirculating.

Natural killer (NK) cell: An innate lymphocyte involved in early defence against infection and in modulating placental vascular development.

Antigen-presenting cell (APC): A cell, such as a dendritic cell or macrophage, that processes and presents antigens to T cells to initiate immune responses.

Microchimerism: The persistence of a small number of cells or DNA from one individual (foetus) within another (mother) following pregnancy, with potential immunological consequences.

Extracellular vesicle: Membrane-bound particles released by cells that carry proteins, lipids and nucleic acids, contributing to intercellular communication at the maternal–fetal interface.

References

1. Human uterine lymphocytes acquire a more experienced and tolerogenic phenotype during pregnancy. Scientific Reports (2017).
2. An altered endometrial CD8 tissue resident memory T cell population in recurrent miscarriage. Scientific Reports (2017).
3. Antigen-specific decidual CD8+ T cells include distinct effector memory and tissue-resident memory cells. JCI Insight (2023).
4. Deciphering decidual leukocyte traffic with serial intravascular staining. Frontiers in Immunology (2024).
5. Visualizing Dynamic Changes at the Maternal-Fetal Interface Throughout Human Pregnancy by Mass Cytometry. Frontiers in Immunology (2020).