Researchers say they are a step closer to developing a predictive test for pre-eclampsia, a dangerous condition which affects one in ten pregnancies.
Women may have pre-eclampsia long before symptoms appear
A team at the University of Leeds has found blood plasma taken from women with the condition contained different chemical levels from those without.
They believe these markers may appear many weeks before symptoms such as high blood pressure manifest themselves.
Pre-eclampsia accounts for 15% of all premature deliveries in the UK.
This is because the only way to completely cure pre-eclampsia is to deliver the baby. Left untreated, the condition can lead to convulsions, kidney failure and serious liver problems.
But prematurely born babies are at risk of a variety of health problems, including developmental delay.
At present, urine tests and blood pressure checks diagnose those women with pre-eclampsia after 20 weeks gestation. The condition is managed for as long as possible with aspirin, and close monitoring.
But Leeds researchers hope that a scan of the blood for chemicals could spot those women at risk far earlier, and lead to better management of the condition.
"It's not a cure, at this stage at least," says Professor Jimmy Walker of St James' University Hospital, who co-authored the research.
"But the earlier we diagnose the better we can control the disease, and the more chance we have of keeping the pregnancy going for longer."
The researchers found certain chemicals such as amino acids increased in concentration when a woman had pre-eclampsia, while others decreased.
They now hope to develop a diagnostic kit within the next five years.
Cutting the number of pre-eclampsia related premature deliveries could save the NHS millions of pounds a year.
Globally, one woman dies every six minutes from the condition - although until an actual cure is found, diagnostic tests are unlikely to help many of these women.
By better understanding the mechanisms of the disease, researchers hope their work may pave the way for more effective treatment.
Mr Donald Peebles, a consultant obstetrician at University College Hospital, said the research was interesting but it was too early to speak of "a breakthrough".
"It will be crucial to establish just how early these markers appear," he says.
"But even if we could know at 16 weeks that a woman had a high chance of developing pre-eclampsia, we remain very limited in what we can do about it - at the moment it is just aspirin, monitoring, and when necessary, early delivery."