Abstract
The concentration of oestriol in the amniotic fluid during the last trimester of normal pregnancy was studied. by transabdominal amniocentesis in 98 pregnant women 144 samples of amniotic fluid were collected. Only women with uncomplicated pregnancies, giving birth to normal infants at term, were included. the results and conclusions were as follows: 1) a calculation of mean levels and upper and lower 95 % probabiliy limits was done for each gestational week in the last trimester. 2) Based on this a smooth curve, indicating the normal concentration area of amniotic fluid oestriol, was drawn. 3) the amniotic fluid oestriol concentration showed little variation before the 33rd gestational week (mean 86-145 μg/l). During the subsequent period the concentration increased to a mean between 559-881 μg/l and a lower limit between 294 and 464 μg/l at term (38—< 42 weeks). 4) Between the amniotic fluid oestriol concentration and the urinary oestriol excretion there was a highly significant correlation. Likewise, serial analyses of amniotic fluid and urinary oestriol showed the same increasing tendency during gestation. 5) Between the amniotic fluid oestriol concentration on the one hand and the infant's birth weight or sex or the weight of the placenta on the other hand there was no significant correlation. 6) Our method is suitable for clinical use, and on the basis of the normal concentration area described we intend to judge the clinical significance of the amniotic fluid oestriol assay as a measure of foetal well-being.