Concentrations of total oestriol, non-conjugated oestriol, human placental lactogen and Oxytocinase in the serum, and total oestrogens in the urine of pregnant women, following the administration of betamethasoneSummary: Prophylactic therapy with betamethasone is used during the last three months of pregnancy, for the prevention of the respiratory distress syndrome in the new born child. This results in changes in some biochemical parameters, which are normally used to monitor the foetoplacental unit. The influence of betamethasone on the concentrations of total oestriol, non-conjugated oestriol, human placental lactogen and oxytocinase in the serum, and on the urinary excretion of total oestrogens was investigated. Both of the serum oestriol fractions and the total urinary oestrogens decrease to 50-60% of their starting values within 1-2 days after the onset of betamethasone therapy. This is thought to be due to the suppression of the foetal hypophysis-adrenal cortex interaction by betamethasone, which results in a decrease in the biogenesis of the oestriol precursor, 16-a-hydroxy-dehydroepiandrosterone sulphate. There are marked individual variations in the time taken to re-establish or to exceed the basal values: 11 days for the non^conjugated oestriol, 13 days for the total urinary oestrogens, and 18 days for the total oestriol in the serum. The purely placental parameters, human placental lactogen and oxytocinase were not influenced by betamethasone therapy; they showed their usual slight increase, which is typical for this period of pregnancy.Einführung ten Beeinflussung der kindlichen Lungenreife durch Betamethason. Bei einer Gesamtzahl von 185 Schwangeren, 1972 würden von Liggins ScHowie (1) zur Prophylaxe des y()n denen ?6 fflit Bet amethason behandelt wurden, traAtemnotsyndroms von Neugeborenen die pränatale The-^ ^ den Neugeborene n in der Betamethason-Gruppe rapie mit hochdosierten Glucocorticoiden eingeführt. Die wesentlich seltener schwere Atemstörungen auf als im Glucocorticoide induzieren eine vermehrte Synthese des . {