The condition, which leads to the deaths of 1,000 babies each year in the UK alone, could be detected as early as the first trimester, a study suggests.
A predictive test could save many lives by enabling closer monitoring of high-risk pregnancies, experts say.
Currently, routine urine and blood pressure checks can pick it up only after 20 weeks.
The condition is managed for as long as possible with aspirin and extra monitoring, but delivery is the only cure.
The work was carried out at St Michael’s Hospital, Bristol, and the University of Bristol. The team measured levels of the chemical in pregnant women at 12 weeks and then at intervals throughout gestation.
They found that in normal pregnancies there was a large increase in the protein by the end of the first trimester, but in women who went on to develop pre-eclampsia it barely increased at all.
Professor Jeremy Pearson, associate medical director at the British Heart Foundation, which funded the research, said: “These researchers have made a vital finding that, if confirmed by other studies, has the potential to translate into a simple test that could potentially save many lives.”