SARS-CoV-2 infection in pregnancy is associated with robust inflammatory response at the maternal-fetal interface

Pregnant women appear to be at increased risk for severe outcomes associated with COVID-19, but the pathophysiology underlying this increased morbidity and its potential impact on the developing fetus is not well understood. In this study of pregnant women with and without COVID-19, we assessed viral and immune dynamics at the placenta during maternal SARS-CoV-2 infection. Viral RNA was only rarely detected in the placentas from SARS-CoV-2-positive women in our cohort, with only 1/11 positive for infection at the maternal-fetal interface. Through bulk RNA transcriptomic analyses, we found that placentas from SARS-CoV-2-positive pregnancies exhibited inflammatory markers of immune activation, even in the majority of samples which did not show local invasion of the virus. These markers are associated with pregnancy complications such as preeclampsia and poor fetal outcomes. Overall, this study suggests that SARS-CoV-2 is associated with immune activation at the maternal-fetal interface even in the absence of detectable local viral invasion. While this likely represents a protective mechanism shielding the placenta from infection, inflammatory changes in the placenta may also contribute to poor pregnancy outcomes and thus warrant further investigation. mRNA profiles of placental villous tissue at term delivery from control and SARS-CoV-2-positive mothers