[Changes of the amniotic fluid proteins on the basis of molecular weight (author's transl)]

Specimens of amniotic fluid obtained from 154 normal pregnancies at various stages and 62 abnormal pregnancies were examined. Total protein was measured by the Lowry method. Fractionation of the protein in the amniotic fluid was analysed by SDS-polyacrylamide gel electrophoresis. 1. Total protein concentration increased from about 375 mg/dl for 10-15 week pregnancies to about 619 mg/dl for 24-27 week pregnancies. From this level it gradually declined, becoming constant at about 210 mg/dl at term. 2. There were 3 cases of gastrointestinal tract obstruction and 2 cases of intrauterine fetal death. High protein levels were found in all of these and in 2 out of 5 cases of hydrops fetalis. 3. In cases of normal pregnancy, the values of the fractions 13-14, 15 and 21-23 increased with period of gestation, and their molecular weights were higher than 56 x 10(3). Values of fractions 7, 10-11 and 12 decreased at the third trimester and their molecular weight were lower than 60 x 10(3). 4. In cases of abnormal pregnancy with high levels of total protein, no fraction increased significantly. 5. In cases of twin pregnancy with low levels of total protein, values of fraction 7, 9 ad 18-19 decreased.