The world's most common cause of infant and maternal mortality has had no good warning test. Preeclampsia, a sharp rise in a mother's blood pressure and a narrowing of blood vessels, can develop around the 20th week of pregnancy; in some cases, that rise becomes a huge spike, causing premature delivery of the baby and possibly death of the mother. Until now, the sole test has been regular monitoring of blood pressure, which detects the condition only after it has started. A new test for a protein, however, might provide an earlier warning.

What the researchers wanted to know: Can levels of the protein PlGF in urine accurately predict preeclampsia? It's a protein that helps blood vessel growth and widening—blood vessels narrow in this disease—so a drop might signal that preeclampsia is on its way.

What they did: Urine specimens from women who had participated in a large preeclampsia study were examined. The women had all given samples at less than 22 weeks of gestation and had all given birth to a live male infant. A total of 118 women had normal pregnancies and were compared with 120 women who had preeclampsia. The researchers looked for levels of PlGF in the urine of these women.

What they found: PlGF levels were a lot lower in the preeclampsia women six to eight weeks before their symptoms became apparent and stayed low once symptoms started. The average level for preeclamptic women was 32 pg/mL, while for normal women it was 234 pg/mL.

What the study means to you: Doctors could develop a simple urine test to predict the onset of disease before serious symptoms start.

Caveats: That test hasn't yet been developed. And though it seems intuitive that earlier detection will lead to better pregnancy outcomes, there's no proof yet—because there hasn't been an early-detection test. Stay tuned.

Find out more: Information about preeclampsia, symptoms, and treatment is available online from the American Academy of Family Physicians.

Read the article: Levine, R.J., et al. "Urinary Placental Growth Factor and Risk of Preeclampsia," Journal of the American Medical Association. Jan. 5, 2004, Vol. 293, No. 1, pp. 77–85.

Abstract online: http://jama.ama-assn.org