[Regulation of the fetoplacental unit. 1. Comparison of the suppressive effect of cortisol and cortisone on estradiol synthesis].

The present study compares the negative feed back action of cortisol and cortison on oestriol production in late human pregnancy. 10 women from the 38th to 40th week of gestation volunteered in this study. All had uncomplicated courses of pregnancy and delivered healthy babies at term. 5 patients received a continuous infusion of 100 mg Cortisol from 10 a.m. to 12 a.m. To the other 5 patients 100 mg Cortison were infused during the same period. Blood specimens (5 ml) were drawn in 60 and 30 minutes intervals from 8 a.m. to 5 p.m. Plasma levels of unconjugated oestriol were measured by radioimmunoassay. The suppression of oestriol levels was nearly identical in both groups: After Cortisol oestriol concentrations decreased from 17.1 +/- 9.1 ng/ml to 6.0 +/- 1.2 ng/ml (p less than 0.001) and after Cortison from 15.5 +/- 5.8 ng/ml to 5.9 +/- 1.8 ng/ml (p less than 0.001), respectively. According to these results the placental metabolism of maternal cortisol to cortison does not impair the negative feed back action of this hormone on the foetal hypothalamus-hypophysis-system.