Placental transfusion has been compared in premature and full-term infants. Blood volume measurements showed that the 5-minute transfusion was similar in full-term and premature infants (47% and 50% increase in blood volume from birth). A larger proportion of the 5-minute transfusion occurred by 1 minute in full-term (76%) than in premature infants (56%). Placental transfusion, by increasing red cell volume, greatly enhanced the severity of neonatal hyperbilirubinemia. Bilirubin concentrations of 15 mg/100 ml developed in only 6% of premature infants when cord clamping was immediate, in 14% when cord clamping was delayed 1 minute, and in 38% after a 5-minute delay in cord clamping.