Increase in bilirubin-binding affinity of serum with age of infant.

The bilirubin-binding affinity of infant serum, as determined by Sephadex gel filtration, began to increase during the first week of life and continued to increase gradually until the age of 5 months, when it reached that of adult serum. This increase might be due to a transition from a fetal to an adult type of serum albumin and/or to a decrease in the concentration in serum of the substances thought to compete with bilirubin for binding to albumin.