Elevated circulating levels of a decidual protein, placental protein 12, in preeclampsia.

The serum concentration of placental protein 12 was measured by radioimmunoassay in 111 apparently healthy pregnant women at 33 to 40 weeks, and the results were compared with those of 39 women with preeclampsia either with or without proteinuria at similar stages of pregnancy. Because the placental protein 12 levels were similar between 33 and 40 weeks of pregnancy, all data were pooled for the analysis of results. The levels were generally higher in preeclamptic patients: 175 +/- 81.5 micrograms/L (mean +/- SD) for preeclampsia versus 112 +/- 38.8 micrograms/L for controls (P less than .001). Those patients with proteinuric preeclampsia had the highest levels (207 +/- 92.1 micrograms/L; P less than .001). In preeclampsia the levels were above the normal 90th percentile in 15 (38%) cases (P less than .001). Because placental protein 12 has recently been found to be synthesized by decidua and not placenta, these results suggest that decidua may be affected in preeclampsia.