PubMed · 2026-04-13
A study of 761 pregnant women found that COVID-19 rarely infects placental tissue in the first trimester, yet still triggers significant immune disruption at the maternal-fetal interface that may harm pregnancy outcomes.
SARS-CoV-2 was detected at low levels in placental tissues from 761 first-trimester pregnancies, with single-cell analysis showing no significant co-expression of ACE2 and TMPRSS2 entry receptors.
Maternal infection significantly elevated immune markers IL-31, IL-5, and GRO-α during acute infection, while increased IgG antibody levels were negatively correlated with TNF-β, suggesting a protective antibody effect.
Infection disrupted WNT and TGF-β signaling pathways in trophoblast cells and altered their differentiation trajectories, despite the virus being largely absent from placental tissue.