Forewarning of preeclampsia.

Scientists have found an early warning sign of preeclampsia, a pregnancy complication marked by high blood pressure. Pregnant women with too much of a protein called soluble endoglin in their blood have a heightened risk of preeclampsia, the researchers say.

Endoglin normally sits on the surface of blood vessels, where it plays a role in vessel dilation and facilitates blood flow. But endoglin can escape these moorings and dissolve in the blood.

Epidemiologist Richard J. Levine of the National Institute of Child Health and Human Development in Bethesda, Md., and his colleagues tested stored second-trimester blood samples from 552 pregnant women. Of these, 72 had developed preeclampsia late in their pregnancies. Those women had blood concentrations of soluble endoglin that were nearly double those found in women who had uncomplicated pregnancies. The warning sign appeared 2 to 3 months before preeclampsia struck, the researchers report in the Sept. 7 New England Journal of Medicine.

The work adds soluble endoglin to a growing list of proteins that, in aberrant supply, signal an increased risk of preeclampsia (SN: 2/14/04, p. 100). For example, pregnant women who are destined to develop preeclampsia often have too little placental growth factor in their blood and too much of a protein that regulates blood vessel growth (SN: 5/10/03, p. 293; 3/8/03, p. 147).

In fact, Levine and his colleagues found that using measurements of soluble endoglin and the ratio of these two other compounds to each other provided even better predictions of preeclampsia than either test did on its own.

The next step is to combine these measurements into a reliable test for preeclampsia that yields few false-positive readings, says Levine.