Bilirubin Metabolism in the Fœtus

IT has been shown that in fœtal liver the enzymatic mechanism for glucuronide formation is poorly developed, while a rapid increase in enzymatic activity occurs during the early neonatal period 1 . The transient hyperbilirubinæmia observed during the first few days of life is believed to be related to this inadequate development of the hepatic conjugating system 1 . Since a significant increase in serum bilirubin concentration usually occurs only after the cord is severed, it has been assumed that during gestation the placenta is responsible for the removal of fœtal bilirubin. It has not been determined, however, whether the placenta has the ability to conjugate the fœtal pigment or whether placental transfer of unconjugated bilirubin occurs from the fœtal to the maternal circulation.