Abstract
•Luteal phase blood Treg levels were significantly lower in the URPL group.•Blood Treg constituted a potential predictor of subsequent miscarriage in URPL.•URPL group showed normal CD4+T, CD8+T, B, NKT, or NK, NK subpopulations.
The aim of this study was to investigate the relationship between pre-pregnancy blood immune status and unexplained recurrent pregnancy loss (URPL), and to evaluate the predictive value of pre-pregnancy blood Treg levels for subsequent miscarriage in patients with URPL. We retrospectively analyzed 76 women who had experienced two or more miscarriages before 24 weeks of gestation for no obvious reason, and 74 women who had achieved live births as controls. Flow-cytometric analysis of peripheral blood CD4 + T cells, CD8 + T cells, NK cells, NKT cells, B cells, NK cell subpopulations (including CD56bright NK cells, CD56dim NK cells, CD56dimCD16+ NK cells, and CD56brightCD16− NK cells) was executed in the luteal phase of women in the URPL and control groups. When we reviewed and analyzed reproductive outcomes in URPL patients, we found that blood Tregs were significantly lower in the URPL group than in the controls (1.89% ± 0.61% vs. 2.15% ± 0.58%, P < 0.01) during the luteal phase pre-pregnancy. However, we discerned no differences among blood CD4+T cells, CD8+T cells, B cells, NKT cells, or NK cells, NK subpopulations (CD56bright NKs, CD56dim NKs, CD56dimCD16+ NKs, or CD56brightCD16− NKs) between the two groups. By implementing receiver operating characteristic (ROC) curve analysis to determine whether Treg levels predicted subsequent miscarriages, we found that the area under the ROC curves was 0.714, and that the cutoff value was 1.35, with a sensitivity of 0.556 and specificity of 0.923. Based on the cutoff value, we divided pregnant URPL patients into two groups, demonstrating that the subsequent miscarriage rates in the low-Treg level group (<1.35%) were significantly higher than those in the normal-Treg level group (>1.35%) (71.43% vs. 14.29%, P < 0.01).
The pre-pregnancy blood Treg level was a potential marker that predicted subsequent miscarriage in women with URPL.