A SIMPLE blood test taken during the first trimester of pregnancy could accurately predict the risk of preeclampsia as early as 18 weeks before symptoms appear, according to research presented at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE 2025).
The study, led by researchers from the Carlos Simon Foundation and iPremom, analysed blood samples from 9,586 pregnant women across 14 hospitals in Spain. In a detailed case-control analysis of 216 participants, the team used cell-free RNA (cfRNA) sequencing and machine learning to detect early molecular signatures of both early-onset (EOPE) and late-onset preeclampsia (LOPE).
Preeclampsia, a pregnancy complication marked by high blood pressure and potential organ damage, often goes undetected until it’s already progressing. Current screening methods miss over half of the cases. In contrast, this new cfRNA-based “liquid biopsy” identified EOPE with 83% sensitivity and 90% specificity, on average, 18 weeks before diagnosis.
“For the first time, we’ve shown that a routine blood test can accurately identify high-risk pregnancies long before symptoms appear,” said first author Dr. Nerea Castillo Marco. “This opens a critical window for prevention and close monitoring.”
The study also shed light on the underlying biology. Nearly half of the predictive signals for EOPE came from genes linked to uterine lining function, supporting theories of early endometrial dysfunction. Meanwhile, LOPE was associated with more systemic changes and occurred later.
A clinical trial is now underway to assess how cfRNA screening could be integrated into routine prenatal care.
Reference
Castillo Marco N et al. Maternal plasma cell-free RNA as a liquid biopsy for first-trimester screening of early and late-onset preeclampsia. Nat Comms (under review) [preprint: https://www.researchsquare.com/article/rs-5684050/latest] & Human Reproduction. ESHRE Annual Meeting, 30th June–2nd July, 2025.
