Perinatal bile acid metabolism: analysis of urinary bile acids in pregnant women and newborns

The metabolism of bile acids in 30 pregnant women was evaluated by analyzing the urinary composition of bile acids during late gestation (weeks 30-41) and again in these women and their newborn infants during the first week after delivery. The levels of individual bile acids were deter- mined by gas chromatography-mass spectrometry after solvol- ysis and hydrolysis of bile acid conjugates. The mean total bile acid/ creatinine ratio in pregnant women decreased from 1.22 pmol/mmol creatinine at 30-32 weeks of gestation to 0.15 Fmol/mmol creatinine at 6-7 days after delivery. The mean percentage of lp-hydroxylated bile acids peaked at 27% at 3-4 days after delivery. In newborn infants, the mean total bile acid/creatinine ratio rapidly increased from 3.39 pmol/ mmol creatinine at birth to 54.33 Fmol/mmol creatinine at 7 days. During this period, large amounts (40-50%) of unsat- urated ketonic bile acids, especially 7~,1 Pa-dihydroxy-%oxo- 5P-chol-1-en-24-oic acid and 7~,12a-dihydroxy-3-oxo-4- cholen-24-oic acid, were observed in the infants' urine.l These data suggest that, during the perinatal period, the for- mation of polyhydroxylated and unsaturated ketonic bile acids probably represents a mechanism for the excretion of bile salts, and that the metabolism of bile acids in both the mother and the infant changes significantly after birth.--=- mura, A, M. Suzuki, T. Murai, T. Inoue, H. Kato, D. Hod, Y. Nomura, T. Yoshmura, T. Kurosawa, and M. Tohma. Perina- tal bile acid metabolism: analysis of urinary bile acids in preg- nant women and newborns.,/ LifiidRuc. 1997. 38: 1954-1962.