Differences in urinary excretion of steroid 21-deoxyketols by women pregnant with a normal or an anencephalic foetus.

During late pregnancy the urinary excretion of steroid 21-deoxyketols, which contain the CH3-CO-C(OH)less than side chain, was 1.16 +/- 0.50 mg/24 h (mean +/- SD n = 9). The mean excretion of these metabolites in 8 pregnancies with an anencephalic foetus showed a significant reduction (P less than 0.01, t-test) to 0.42 +/- 0.18 mg/24 h. Six untreated non-pregnant women and 7 taking oral contraceptives which contain oestrogen had steroid 21-deoxyketol excretions of 0.26 +/- 0.09 mg/24 h and 0.19 +/- 0.09 mg/24 h respectively. These results imply that the adrenal of the normal foetus makes a contribution to the secretion of those steroids which are ultimately excreted by the mother as 21-deoxyketols.