Evaluation of T-cell subsets in pregnant women infected with SARS-CoV-2

•The CD3+ total T cell ( p = 0.001), CD3+CD4+ helper T cell ( p = 0.011), Treg ( p = 0.001), and Treg/Th17 ratio ( p = 0.001) were found to be lower in pregnant women infected with SARS-CoV-2.•This difference was associated with the development of pneumonia but not with adverse pregnancy outcomes.•SARS-CoV-2 was not detected in any newborn. 20.4% of newborns from mothers infected with SARS-CoV-2 and 6.8% of newborns from mothers not infected with SARS-CoV-2 were admitted to the neonatal intensive care unit.•13 patients in the SARS-CoV-2 group were delivered prematurely due to the worsening of the COVID clinic. 5 newborns died due to prematurity in this group Immune responses to SARS-CoV-2 are the main cause of tissue damage in coronavirus disease 2019. However, the pathophysiological mechanism of the disease has not been fully elucidated. The aim of this study was to examine T cell subsets of pregnant women infected with SARS-CoV-2 and evaluate the relationship between the possible differences in trimesters and clinical findings of the disease. Fifty-six pregnant patients with SARS-CoV-2 and 61 healthy pregnant controls were included in the study. T cell subsets were analyzed by flow cytometry. The CD3+ total T cell (p = 0.006 and p = 0.027) of pregnant patients infected with SARS-CoV-2 in second and third trimesters was found to be lower than in the control group. CD3+CD4+ helper T cell (p = 0.035), Treg (p = 0.001), and Treg/Th17 ratio (p = 0.001) were found to be lower in the third trimester patients infected with SARS-CoV-2 than in the controls. Significant decreases were observed only in the Treg (p = 0.001) and Treg/Th17 ratio (p = 0.001) in the first trimester patients infected with SARS-CoV-2 compared to the controls. When trimesters were compared in terms of T subsets, no difference was found (p > 0.05). The CD3+ total T cell (p = 0.001), CD3+CD4+ helper T cell (p = 0.011), Treg (p = 0.001), and Treg/Th17 ratio (p = 0.001) were found to be lower in pregnant women infected with SARS-CoV-2. This difference was associated with the development of pneumonia but not with adverse pregnancy outcomes.