Maternal COVID-19 infection and subacute placental histopathology

Abstract

Background: The emergence of coronavirus disease 19 (COVID-19) as a novel zoonotic disease has been of international concern, with recent studies highlighting the potential association of COVID-19 with placental vascular dysfunction.1,2 Because the increased incidence of histopathological lesions could imply an aetiologic relationship with SARS-CoV-2 infection, this study aims to audit the spectrum of subacute placental disease occurring in COVID-19 positive mothers.Methods: Histopathological reports were obtained from Liverpool Hospital from 18 March 2020 to 18 March 2022 and subjected to retrospective histopathological report audit. Three hundred and five placentas from mothers with history of COVID-19 infection during pregnancy were compared with 305 randomly selected controls with no reported COVID-19 infection. Information obtained included maternal age, fetal gestation at delivery, macroscopic measurements and 12 histopathological variables. Missing data was imputed using a random forest algorithm, with downstream multivariate statistical analysis. Validation of findings was performed via non-linear principal component analysis (NLPCA). Results: A significant increase in mean placental weight was observed in mothers with a history of COVID-19 (COVID-19 cohort 480g, control cohort 423g, p < 0.0001). Median gestation was significantly increased within the COVID-19 cohort at 38.2 weeks compared to 36.5 weeks in controls (p <0.0001). Surprisingly, there was no increase in histopathological lesions within the COVID-19 cohort. Similar findings were confirmed with NLPCA. These findings highlight the possible resistance of the placental disc to COVID-19 infection and the utility of utilising imputation and NLPCA in the study of potential new pathological entities.