It may be one day possible to predict which women will develop the dangerous pregnancy complication called pre-eclampsia -- even weeks before symptoms appear.

An international team of doctors says they've discovered 14 telltale metabolites that appear in the blood in early pregnancy that signal an increased risk for pre-eclampsia.

The researchers hope the discovery could one day mean a simple, cheap blood test for the life-threatening condition.

Pre-eclampsia is a condition that affects about five per cent of pregnancies and is marked by a spike in high blood pressure and protein in the urine after the 20th week of pregnancy. If left untreated, the condition can lead to seizures and the death of the mother.

The only way to treat pre-eclampsia is to deliver the baby immediately, a decision that sometimes leads to the death of the baby.

It's not clear what causes the condition. Although symptoms don't usually appear until the second half of pregnancy, the condition is thought to begin in early pregnancy, because of a defective development of the placenta.

Dr. Louise C. Kenny, this study's lead researcher and professor of obstetrics and gynecology at University College Cork, in Ireland, said that in order to one day develop and effective treatment or prevention method for pre-eclampsia, doctors need to be able to spot the condition early.

"We need to be able to tell who is at risk and who is not," she said in a news release.

For this study, Kenny's team studied 60 healthy, first-time mothers who developed pre-eclampsia later in pregnancy. They were matched with a control group of 60 women who had had uncomplicated pregnancies.

The women -- mostly white New Zealanders -- had blood screening at 15 weeks into their pregnancy. Researchers narrowed in on 14 telltale metabolic biomarkers in the women who went on to develop the condition but that were not found in the healthy women.

The study's second phase validated the findings, by using a different group of women from Adelaide, Australia. These women were younger, with an average age of 22-23, and were more ethnically diverse.

Women who developed preeclampsia were matched with a control group of 40 women with healthy pregnancies. Of those who developed the condition, 39 were found to have had the same 14 metabolites.

The researchers say their aim now is to develop a blood test in the next five years that could be used on all pregnant women to assess their preeclampsia risk, said Dr. Phil Baker co-investigator of the study and dean of Medicine and Dentistry at the University of Alberta.

The research appears in the October issue of Hypertension.