Abstract
In 6 healthy women in late pregnancy the urinary oestriol fraction increased considerably following Infusion of 25 IU corticotrophin (ACTH). Oestrone and oestradiol did not rise in a comparable extent. 6 patients with intrauterine foetal death and 3 women in the 10th and 11th week of pregnancy showed no increase of oestriol after ACTH. The results indicate a conversion of ACTH-dependent steroid precursors to oestriol in late pregnancy by the intact foeto-placental unit.