Neonatal indirect hyperbilirubinaemia in twins.

Neonatal indirect hyperbilirubinaemia in 21 pairs of twins was compared and studied during the first postnatal week. Peak bilirubin concentration and the persistence of icterus was similar in the two sets of twins, but considerable individual inter-twin differences could be obeserved. Various postnatal parameters and inter-twin differences in these parameters were correlated with differences in hyperbilirubinaemia. It has been concluded that physiologic or idiopathic hyperbilirubinaeamia is closely similar in twins, probably due to the similar functional maturity of bilirubin clearance mechanisms. Individual variations were related to differences in caloric intake: the higher the caloric supply the lower was the maximum bilirubin concentration.