[The pattern of distribution of free amino acids in human amniotic fluid related to the duration of pregnancy. Part II: Changes in concentration in pathological pregnancy (author's transl)].

18 free amino acids from 196 specimens of amniotic fluid of pathological pregnancies between the 28th and 41st week of pregnancy were measured by gaschromatography. The concentrations of the amino acids in amniotic fluid in normal and pathological pregnancies were analysed by statistical methods. There were only minor differencies of concentration of free amino acids in the amniotic fluid between normal and pathological pregnancies with the exception of hydroxyproline. This was found in a significantly higher concentration in the amniotic fluid of the pathological group. Supposing that the materno-fetal as well as the feto-maternal amino acid exchange may be reduced by the placenta insufficiency, the significantly higher concentration of hydroxyproline in the amniotic fluid during pathological pregnancies may be caused higher fetal urine excretion of hydroxyproline into the amniotic fluid. The increase of hydroxyproline in the amniotic fluid of pathological pregnancies is probably an early diagnostic parameter of an impaired transplacental exchange -- placenta insufficiency.