RNA test could predict pre-eclampsia months before symptoms appear

A 'liquid biopsy' blood test in the first trimester of pregnancy could help identify women who are at risk of developing pre-eclampsia, according to research presented at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE) in Paris.

Pre-eclampsia is a complication that can develop in pregnancy, causing high blood pressure, and can be fatal or cause organ damage. The test searches fragments of RNA floating in the bloodstream (cell-free RNA or cfRNA) for molecular signals from tissues including the uterus and the placenta. The test was able to predict pre-eclampsia in 83 percent of cases, compared to less than half in standard tests.

'For the first time, we've shown that a routine blood sample in the first trimester can give an early warning for pre-eclampsia with high accuracy, well before symptoms appear,' said the study's first author, Dr Nerea Castillo Marco from the Carlos Simón Foundation in Valencia, Spain. 'Identifying high-risk pregnancies this early opens a crucial window for preventive treatment and closer monitoring to protect mothers and babies.'

More than 9,500 pregnant women took part in the study, across 14 Spanish hospitals. Of those who went on to develop pre-eclampsia, the first-trimester blood test identified 83 percent, on average 18 weeks before they were diagnosed.

A smaller group of more than 200 patients gave blood samples at three intervals during pregnancy to investigate whether the test could predict and distinguish between early-onset pre-eclampsia and late-onset pre-eclampsia. On average, the late-onset condition was predicted almost 15 weeks prior to diagnosis.

'We urgently need better tests to identify those at risk of pre-eclampsia, a condition with high morbidity and mortality for both mother and child,' Rebecca Reynolds, professor of metabolic medicine at the University of Edinburgh, who was not involved in the study, told BioNews. 'These findings do suggest that a novel blood test holds promise for prediction of both early- and late-onset pre-eclampsia so that preventative treatments and/or monitoring could be better targeted to those at risk.'

The researchers discovered that there was very little overlap between the molecular signals predicting early- and late-onset pre-eclampsia, indicating that these are biologically different conditions. The early onset condition showed molecular changes in tissues including the placenta and endometrium, as well as the kidney, brain and lungs. In the late-onset condition, immune pathways were more prominent.

Professor Karen Sermon, Chair of ESHRE, said that in addition to the test's potential use in prenatal care, 'this research increases our understanding at a molecular level of a complex pathology that remains poorly understood.'

According to project leader Dr Tamara Garrido, the test could start being used in clinical settings as early as next year.