A prospective study on the rise of serum bilirubin during the first 24 hour
s of life has been carried out in a sample of 343 newborns from the populat
ion of Rome. The rise of serum bilirubin level during the first 24 hours of
life depends on season of birth showing a minimum in the Autumn. The pheno
menon is much more marked in female than in male newborn infants. Recent st
udies suggest a beneficial action of bilirubin due to its protective effect
from secondary oxidants. Since the newborn infant is very sensible to oxid
ative damage, it is possible that seasonal variation of bilirubin level dur
ing the first few days of life may influence further development and suscep
tibility to pathological manifestations.