Chen Y, Huang P, Han C, et al. - Placental factors are reported initiating preeclampsia (PE), which is a pregnancy‐associated condition. Researchers have described the causative role of placental extracellular vesicles (pcEVs) in hypertension and proteinuria in pregnant and non‐pregnant mice. They here conducted an observational study with both case‐control and longitudinal designs. Blood samples and clinical information were gathered from 54 PE patients, 33 normally pregnant women with at 30‐36 gestational weeks and on postpartum days 1 and 4 for the cross‐sectional study, and at 22‐31, 32‐35, and 36‐40 weeks for the longitudinal study. In addition, they recruited non‐pregnant women. Analyses revealed significant elevation of placental, platelet‐, and endothelial cell‐derived extracellular vesicles (EVs) in PE patients, however, only pcEVs were identified as predictive of PE. They suggest a causal role of these EVs in the pregnancy‐induced hypercoagulability.