Evaluation of the lymphocyte population and placental inflammation in pregnant patients with moderate or severe COVID-19 forms - a secondary analysis.

Aim: In this secondary analysis, we aimed to characterize the lymphocytes population and placental inflammation in pregnant women with moderate and severe coronavirus disease 2019 (COVID-19) forms.

Patients, materials and methods: In the analysis of this prospective evaluation, we included 26 pregnant women at term with moderate and severe COVID-19 forms that were evaluated in a tertiary maternity center in a one-year timeframe. Clinical data, along with blood immunophenotyping results and placental histopathological examinations were comparatively evaluated between two study groups depending on the COVID-19 severity: Group 1 (moderate COVID-19, n=14 patients) and Group 2 (severe COVID-19, n=12 patients).

Results: Pregnant patients with severe COVID-19 presented significantly lower total amount of lymphocytes (p<0.001), T-lymphocytes (p=0.009), cluster of differentiation (CD)4+ T-cells (p=0.002), B-lymphocytes (p=0.001). Also, the number of CD4+ T-cells (p=0.01), CD8+ T-cells (p=0.02) and B-lymphocytes (p=0.002) was lower enough for cases with severe COVID-19.

Conclusions: Lymphocytopenia could be a useful hematological marker for risk stratification of COVID-19 in pregnant women at term. A vertical transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) cannot be confirmed in this study, mainly because of the limited sample size and short timeframe between infection and birth.