Levels of placental protein 10 (PP 10) in maternal serum in normal and pathologic pregnancies.

Concentrations of placental protein 10 (PP 10) were measured by radioimmunoassay and found to be detectable but very low in nonpregnant women and in men. In an assay of 223 samples from normal pregnancies, the mean PP 10 level was 2.7 +/- 1.0 ng/ml (mean +/- SD) at 6 to 7 weeks of gestation. The level of PP 10 in maternal sera increased gradually as pregnancy progressed to a high of 40.2 +/- 19.0 ng/ml at 38 to 39 weeks, followed by a slight decrease to 28.9 +/- 15.6 ng/ml at 40 to 41 weeks. The coefficients of variation were 8.6 to 16.2% in diurnal variation and 10.3 to 34% in day-to-day variation. Relatively lower PP 10 levels were observed in maternal sera in threatened abortion with poor prognosis, toxemia of pregnancy, intrauterine fetal death and placenta previa.