[The pattern of distribution of free amino acids in human amniotic fluid related to the duration of pregnancy. Part I: Changes in concentration in normal pregnancy (author's transl)].
Gas-chromatographic measurement of 18 free amino-acids from about 500 specimens of amniotic fluid between the 10th and 41st week of pregnancy. Statistical methods showed different concentrations of amino-acids in amniotic fluid during pregnancy. Serine, cysteine, methionine and tryptophane show constant concentration. Valine tyrosine and hydroxyproline continuously decrease. The other amino acids tested here show a biphasic course of concentration, falling by about 40-70% between the 10th and the 30th week after which they remain stable. Alanin, threonine, glycine and ornithine show a clear increase of concentration. This diversity of concentration of amino-acids during pregnancy hints at the importance of various factors for the composition of amniotic fluid.