Evidence for trans-placental transmission of SARS-CoV-2 remains contradictory, where some studies have shown placental infection and visualization of coronavirus invasion into placenta and some studies have shown no evidence for this. In a recent case study report in published recently in JCI, authors show a woman with COVID-19 in the second trimester of pregnancy, who had severe hypertension, coagulopathy, and preeclampsia.
The authors found that on histological examination, that the placenta had diffuse perivillous fibrin and an infiltrate of inflammatory macrophages and T cells, being consistent with histiocytic intervillositis. SARS–CoV-2 was localized predominantly to the syncytiotrophoblast cells and electron microscopy revealed a well-preserved ultrastructure of the placenta.
The authors conclude from this case that acute placental infection with SARS–CoV-2 may have potentiated severe, early-onset preeclampsia. Whether this is a common or rare occurrence remains to be seen.
Hosier et al., 2020. SARS–CoV-2 infection of the placenta. Journal of Clinical Investigation