Amino acid composition of amniotic fluid, maternal and umbilical vein serum in intrahepatic cholestasis of pregnancy, pre-eclampsia and rhesus incompatibility.

The levels of free amino acids in maternal and umbilical venous serum and in amniotic fluid were determined in 7 patients with normal pregnancy, 11 with intrahepatic cholestasis of pregnancy, 4 with pre-eclampsia and 9 with rhesus incompatibility. In maternal venous serum there were only small differences in the amino acid concentrations in complicated pregnancies when compared with normal subjects, and the only statistically significant difference was a lowered level of histidine in intrahepatic cholestasis. In umbilical venous serum, as in amniotic fluid, the amino acid concentrations were generally elevated in intrahepatic cholestasis of pregnancy and generally decreased in rhesus incompatibility when compared with control values, and in amniotic fluid the concentration of 13 amino acids was significantly higher in intrahepatic cholestasis than in normal pregnancy. Thus, the placental amino acid transfer seems to be increased in intrahepatic cholestasis of pregnancy and slightly decreased in rhesus incompatibility, and changes in the placental transfer system are parallel for most amino acids.