Immunoradiometrical measurement of tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125) in pregnancy and at delivery.

Using conventional radioimmunoassay kits, we measured concentrations of two cancer-related antigens, tissue polypeptide antigen (TPA) and cancer antigen 125 (CA125) throughout gestation and at delivery. The maternal serum was collected from 147 pregnant women between 5 and 43 weeks gestation and 27 women were studied at delivery at which time samples of maternal blood, umbilical artery and vein blood as well as amniotic fluid were collected. The various concentrations of TPA and CA125 were compared with placental weight and infant birth weight. The results are summarized as follows: (1) Mean TPA levels in maternal serum increased with advancing gestation and rose above 110 U/l (upper non-pregnant limit) from 35 weeks onwards. Mean CA125 levels rose above 35 U/ml (normal non-pregnant upper limit) before 9 weeks gestation and thereafter fell. Both levels were markedly raised immediately after delivery. (2) In umbilical artery and vein serum, mean TPA levels were slightly raised. However, there were no significant differences between TPA levels in maternal serum and matched serum from the umbilical artery and vein. Mean umbilical CA125 levels were below 35 U/ml, while mean CA125 levels were significantly higher in the corresponding maternal serum. (3) The concentrations of TPA and CA125 were extremely high in amniotic fluid. The mean values reached 3604 U/l and 2187 U/ml, respectively. (4) None of the concentrations of TPA and CA125 in those pregnancy-related body fluids correlated significantly with birth weight, placental weight or fetal sex. These findings suggest that the production of these two cancer-related antigens is not by the fetus but the placenta.