A single blood sample can detect whether pregnant women are at risk of pre-eclampsia, new research has found.
Genetic material has been identified by researchers after analysing the blood of expectant mothers.
They suggest the findings could help spot complications before symptoms were experienced.
Pre-eclampsia mostly impacts women during the second half of pregnancy and is often found during checks for high blood pressure and protein in the urine.
In some cases, women can experience swelling of the feet, ankles, face and hands, severe headache, vision problems or pain just below the ribs.
The condition affects up to one in 12 pregnancies and is a significant cause of maternal morbidity.
It is also a cause of a higher risk of cardiovascular disease.
While most cases of pre-eclampsia are diagnosed in the third trimester when the woman experiences symptoms, researchers suggest this study could widen the window of detection and lead to quicker intervention.
Professor Rachel Tribe, from the department of women and children's health at King's College London, said: "Using a cutting-edge sequencing approach, we were able to detect cell-free RNA (cfRNA) in the blood of pregnant women.
"These provided a molecular signature that can be used to identify women at risk of pre-eclampsia.
"Excitingly, this requires only a single blood sample and has potential to identify women at risk much earlier in pregnancy so that they can be more closely monitored and treated by the clinicians involved."
The team studied 2,500 blood samples from cohorts that included multiple ethnicities, nationalities, socioeconomic contexts and geographic locations.
They examined the anonymised cell-free RNA (cfRNA) profiles - signals from the foetus and pregnant mother's tissues - that reflect foetal development and healthy pregnancy progression.
Researchers identified the signals which deviate from those of a healthy pregnancy.
Using machine-learning to analyse tens of thousands of RNA messages from the mother, baby and placenta, the Mirvie RNA platform can identify 75% of women who go on to develop pre-eclampsia, the study suggested.
Researchers hope this test can be widened to investigate other pregnancy complications, such as preterm birth.
The study, published in Nature, involved researchers from King's College London and Guy's and St Thomas' NHS Foundation Trust in partnership with Mirvie.
The research was supported by the National Institute for Health Research (NIHR) through the NIHR Guy's and St Thomas' Biomedical Research Centre and an NIHR Doctoral Research Fellowship.
