Placental Pathology After SARS-CoV-2 Infection in the Pre-Variant of Concern, Alpha / Gamma, Delta, or Omicron Eras.

The goal of this study is to describe placental pathology after infection with SARS-CoV-2 before the predominance of variants of concern (pre-VOC) and during eras of predominant transmission of the Alpha & Gamma (co-circulating), Delta, and Omicron variants. We used county-level variant data to establish population-level variant proportions, SARS-CoV-2 PCR to identify cases, and IgG serology to exclude latent infections from controls and histopathologic examination to identify placental pathology. We report findings in 870 placentas from pregnancies complicated by SARS-CoV-2 including 90 with infection in the Alpha/Gamma era, 60 from the Delta era and 56 from the Omicron era. Features of maternal vascular malperfusion (MVM), including decidual arteriopathy, were significantly more frequent after SARS-CoV-2 infection. The risk of these findings varied over time, with the highest rates in the Delta era. Increased COVID-19 severity and the presence of comorbidities strengthened these associations. MVM is a feature of SARS-CoV-2 infection in pregnancy. Lesion frequency changed with the predominant circulating virus and should be considered with new variants.