A UK hospital is testing a home spit kit designed to help mums-to-be spot if they are at risk of pre-eclampsia.
Pre-eclampsia can be symptomless
One thousand women in Chichester will try the test that reads saliva for tell-tale markers of impending kidney problems linked with the condition.
It is expected to be more reliable than traditional blood pressure and urine checks, the Chemistry & Industry magazine reports.
Pre-eclampsia can be symptomless and kills up to 1,000 UK babies every year.
Up to one in 10 pregnant women can get pre-eclampsia, with one in 50 suffering severe problems.
Globally, one woman dies every six minutes from the condition, according to Action on Pre-eclampsia.
Pre-eclampsia, caused by a defect in the placenta, which supplies nutrients and oxygen to the foetus, happens towards the end of pregnancy and causes high blood pressure and kidney problems.
There is no cure, other than delivery of the baby and removal of the placenta.
Prompt detection and intervention can save lives.
In preliminary trials, a prototype of the saliva test accurately identified women with pre-eclampsia.
Results from the St Richard's Hospital trial are expected early next year.
The ultimate aim is to develop a colour-coded "traffic light" detection kit for expectant mothers to use at home.
For example, a red reading would indicate high levels of urate in the saliva which may mean pre-eclampsia.
The woman should then have further checks with her hospital or GP to see if she is at risk.
Developer Brian Owen-Smith, a retired rheumatologist from St Richard's, envisages his test would add to rather than replace existing pre-eclampsia checks.
He explained: "Blood pressure and urine tests are not always reliable. Not all pregnant women with high blood pressure will have pre-eclampsia.
"And a positive urine test might be down to an infection rather than pre-eclampsia.
"The saliva test is a very useful add on. It is so simple, quick and cheap."
He hopes the test will become commercially available in the near future.
Michael Rich of Action on Pre-eclampsia said: "This could be a potentially great complementary test. We look forward to seeing the results of the trial."