Elevated percentage of CD3+ T cells and pregnancy outcome in women with recurrent pregnancy loss

Background: Even though the immune factor is not yet established as a cause of recurrent pregnancy loss (RPL), tons of other studies have shown that a significant proportion of immune abnormalities exist in RPL. Methods: We conducted a retrospective cohort study with 850 women who were diagnosed with RPL. The percentages of CD3(+), CD3(+)CD4(+) and CD3(+)CD8(+)T cells of each participant, detected by flow cytometry, were obtained before pregnancy and at 6 weeks of gestation as part of their routine medical examination. Results: Peripheral blood CD3(+) T cells prior to pregnancy (at baseline), increased significantly in women who had a miscarriage compared with the subsequent live birth group. Moreover, the percentage of CD3(+) and CD3(+)CD4(+) T cells during pregnancy increased significantly as compared with the baseline level. After adjusting for potential confounders, the multiple regression equation showed that the CD3(+) T cells < 67.84% was associated with the risk of miscarriage (OR 1.05, 95% CI, 1.01 to 1.11, p = .04). Additionally, a nonlinear relationship was observed between the percentage of CD3(+) T cells and the risk of miscarriage. Conclusions: The risk of miscarriage increased as the percentage of population with CD3(+) value below 67.84% has increased, nevertheless, the miscarriage risk did not increase further when the level of CD3(+) T cells was > 67.84%.