The neutral steroids derived from their conjugates present in a pool of bile from 20 human foetuses were analysed by gas—liquid chromatography and gas chromatography— mass spectrometry. Ten monosulphates, twelve disulphates and seven glucuronides were detected, but no free steroids were found. Both saturated and unsaturated steroids of the C19- and C21-series were detected. The glucuronides of 5β-pregnane-3α,20α-diol, 5α-pregnane-3β,16α,20α-triol and 3α-hydroxy-5β-pregnan-20-one as well as the monosulphate of 16α-hydroxydehydroepiandrosterone were present in the highest concentrations. Other major components were the monosulphates of dehydroepiandrosterone, pregnenolone and 16α-hydroxypregnenolone and the disulphates of 5-androstene-3β,17α-diol, 3β, 17β-dihydroxy-5-androsten-16-one and 5β-prenane-3ξ,20α,21-triol. The total concentration of the monosulphate conjugates was 435 μg/100 g sample (wet weight), of the disulphates 363 μg/100 g and of the glucuronides 815 μg/100 g.
Many of the compounds detected have previously been found in the foetal liver and intestinal contents. It is therefore concluded that during early and mid-gestation the foetal liver is already excreting many steroid conjugates through the biliary tract into the intestinal canal. As in other foetal compartments, considerable amounts of steroid sulphates were detected. However, the presence of steroid glucuronides in the bile suggests that the formation of hepatic glucuronides already occurs during the foetal period.