Chemical dearth hints at preeclampsia.

Women who have preeclampsia, a dangerous pregnancy complication marked by high blood pressure, also have unusually low concentrations of a fatty acid derivative called prostacyclin, a new study shows.

Prostacyclin hinders blood clotting and relieves high blood pressure by dilating blood vessels. Its counterpart, thromboxane, abets clotting and constricts vessels. The two normally work in harmony. However, in preeclampsia, this balance tips toward thromboxane late in pregnancy. Severe preeclampsia can lead to convulsions, coma, and death.

Urine samples taken from 134 pregnant women who later developed preeclampsia showed prostacyclin concentrations that were 17 percent lower than those in samples from 139 women who didn't experience the condition. Notably, the difference appeared before any signs of preeclampsia. Thromboxane concentrations were not significantly higher in the women who later showed preeclampsia, the scientists report in the July 28 JOURNAL Or THE AMERICAN MEDICAL ASSOCIATION.

Although the study establishes that a prostacyclin deficiency occurs early in women who go on to develop preeclampsia, it doesn't establish that this is the primary cause of the condition, says coauthor James L. Mills of the National Institute of Child Health and Human Development in Rockville, Md. Nonetheless, the finding suggests that restoring proper amounts of this compound might help prevent preeclampsia, he says.