The Influence of Maternal Immune Events on the Establishment of Maternal Microchimerism

Abstract

Maternal microchimerism (MMc), or the transfer of maternal cells to the offspring, has been associated with immune modulation and improved health outcomes in newborns. Using data collected from a prospective cohort, we assessed how maternal immune events during pregnancy, including vaccinations and illnesses, influenced the odds of detecting MMc in cord blood. Additionally, we examined the dynamic changes that occurred in the maternal T cell repertoire across trimesters. We observed that vaccination was associated with higher odds of detectable cord blood T cell MMc (OR: 1.68, 95% CI: 0.42- 6.75) and that this effect was modified by gestational age, with the strongest effect with vaccination in first trimester (OR: 1.38, 95% CI: 0.36- 5.29). We also found that T cell repertoire varied greatly across individuals and by trimester. These findings suggest that the timing of immune exposures and the individual immune history of the mother are important factors influencing the transfer of maternal T cells to the fetus, with potential implications for offspring immune development and health.