[Bilirubin UDP-glucuronyltransferase activity in human fetal liver homogenates].

The bilirubin UDP GT-activity of the liver was studied from week 15 of pregnancy in 23 human fetuses and mature and immature dead newborns, respectively. No measurable bilirubin UDP GT-activity was found up to week 26 of pregnancy. The development of enzymatic activity presumably starts only postnatally, irrespective of gestational age of birth weight. Up to the fifth day the bilirubin UDP GT-activity is less than 0.2 mg of conjugated bilirubin/g liver/h, reaching in the second week values that correspond to approximately 20--30% of adult values. This activity is sufficient to prevent a clinically important hyperbilirubinemia because the concentration of unconjugated serum bilirubin was in all children below 12mg/100 ml.