Concentration of placental protein 10 (PP10) in maternal serum and amniotic fluid throughout normal gestation and in pregnancy complicated by fetal growth retardation

PP10, a new placental glycoprotein, was studied by a specific and sensitive double-antibody radioimmunoassay in maternal serum and other body fluids throughout pregnancy. The mean value of serum PP10 in healthy nonpregnant individuals was approximately 10 microU/l. During normal pregnancy it rose to 3,500 microU/l. The rate of rise was obtained from 78 normal pregnancies with 279 single assay values from weeks 6-40. The shape of the curve resembled that for other placental proteins (HPL, SP1). PP10 levels in amniotic fluid were measured in 145 samples from weeks 13-55 of normal pregnancies and at term. The mean concentration was 500 microU/l until week 18 and then rose slowly. Cord blood contained only trace amounts. PP10 was not found in maternal urine. The concentration in maternal serum and amniotic fluid was higher in twin pregnancies than in singleton pregnancies. In 46 cases with low birth weights the PP10 levels in maternal serum were significantly lower than normal. Simultaneous measurements of PP10 and E3, HPL and SP1 were made in 17 individual follow-up's. PP10 was comparable with E3 and appeared to be better than HPL and SP1 in predicting intrauterine fetal growth retardation.