AbstractObjectiveOur objective was to investigate whether serum concentrations of a novel anti‐angiogenic factor, soluble endoglin (sEng), could predict placental abruption.MethodsIn a nested case–control study of nulliparous pregnancies, we examined levels of sEng in serum collected prospectively from 31 women who later developed placental abruption and from 31 normal controls. All serum specimens were collected before the onset of hypertension or abruption and before labor or delivery. Serum sEng was compared within three gestational age intervals: early‐ (<20 weeks), mid‐ (21–32 weeks), and late (≥33 weeks) pregnancy.ResultsThere was no significant difference in sEng between abruption cases and controls in early pregnancy. sEng was significantly elevated among abruption cases at 21–32 weeks (10.7 vs 5.9 ng/mL, P < 0.01). Subgroup analyses revealed no differences in sEng concentrations at any gestational age interval between cases with abruption without hypertension and healthy controls. Among women who developed hypertension and placental abruption, sEng was not significantly increased in early pregnancy, but was in mid‐pregnancy (19.3 vs 5.5 ng/mL, P = 0.002) and in late pregnancy (15.6 vs 9.5 ng/mL, P = 0.04).ConclusionsSerum levels of the anti‐angiogenic factor sEng are elevated prior to the development of hypertension and placental abruption. These elevations are not apparent until the late second trimester (26–27 weeks, on average), but they persist from this time in gestation onward. sEng may be useful for identifying pregnant women at risk for abruption and hypertension. Copyright © 2008 John Wiley & Sons, Ltd.