Comparative clinical and placental pathologic characteristics in pregnancies with and without SARS-CoV-2 infection

To compare the clinical and morphological characteristics of the "mother-placenta-fetus" system in high risk pregnant women of three groups: no SARS-CoV-2 infection, mild SARS-CoV-2 infection, and severe SARS-CoV-2 infection.

A case-control study was performed for all deliveries, at 28 weeks' gestation or greater, who had standard indications for placental pathologic examination. Three groups were formed: (1) control group (no SARS-CoV-2 infection), (2) mild SARS-CoV-2 infection, (3) severe SARS-CoV-2 infection. High-risk pregnancies were registered in all cases in the study groups. The examination of the placenta and the selection of fragments of placental tissue were carried out in accordance with the consensus recommendations of the Amsterdam Placental Workshop Group. The sections were subjected to standard processing and stained with hematoxylin and eosin according to the standard protocol. All cases were reviewed by two pathologists, which did not know any information on pregnancy outcome and clinical data. Statistical analysis was performed using SPSS, p<0.05 was considered statistically significant.

Women with severe SARS-CoV-2 infection had an increased rate of multimorbidity including diabetes, chronic hypertension and obesity (p<0.01) compared with the other groups. Placentas at severe COVID-19 course were damaged by both chronic and acute injuries, in comparison to the mild and control groups (p<0.001). Also an important finding in severe COVID-19 was diffuse necrosis of the villous trophoblast - homogenization, diffuse circular eosinophilic masses surrounding the chorionic villi.

Women with multimorbidity are an "at-risk" subgroup for severe SARS-CoV-2 infection and greater likelihood of both placental damage and perinatal hypoxic-ischemic events. These results suggest that patient education, SARS-CoV-2 disease monitoring and preventive measures would be of benefit to this group.