Analysis of amniotic fluid, maternal plasma, and cord blood for a human breast gross cystic disease fluid protein.

Amniotic fluid was analyzed for the presence of the 15,000 monomer molecular size glycoprotein found in human breast gross cystic disease fluid (GCDFP-15). From 24 weeks' gestation a log-linear increase in levels of GCDFP-15 was noted. The levels of GCDFP-15 doubled every 16 to 28 days, and the highest value recorded was 7,200 ng/ml. At delivery, levels of GCDFP-15 in cord blood plasma were in a background range (mean, 8 ng/ml). Maternal plasma levels of GCDFP-15 were one to tenfold higher in the third trimester of pregnancy when compared to those in nonpregnant women. Since saliva is known to contain high concentrations of GCDFP-15 (10 to 70 micrograms/ml), it is proposed that the levels in amniotic fluid originate from saliva and tracheobronchial secretions.