[Serum oestriol: a parameter of the function of the feto-placental unit (author's transl)].

The determination of serum oestriol is known to be a useful parameter of the function of the feto-placental unit. In order to derive the normal range on application of the radioimmunoassay technique, the serum oestriol level was determined in 242 gravidae during the second half of pregnancy. The pregnancies were all uncomplicated and ended with the delivery of a healthy baby at term. The statistical mean and 4 confidence intervals were calculated for each gestational week individually. During the second half of pregnancy there was a continuous gradual increase in serum oestriol; between the 34th and 38th gestational week there was a further steep increase, followed by a decrease from the 39th gestational week onwards. The usefulness of this method is illustrated on the basis of case reports of 10 high-risk pregnancies in which oestriol determination is compared with the clinical findings and HPL determination.