What condition is characterized by increased bilirubin levels in newborns?

Jaundice is a condition that occurs when there is an excess of bilirubin in the bloodstream, leading to a yellowish tint in the skin and the whites of the eyes. In newborns, this condition is relatively common due to the immaturity of their liver function, which may not be fully equipped to process bilirubin effectively right after birth. Bilirubin is a byproduct of the breakdown of red blood cells, and while most infants will experience a mild form of jaundice called physiological jaundice, some may develop more significant levels that require monitoring and potential treatment.

The presence of jaundice in newborns can indicate various underlying issues, including hemolysis or liver problems, and should be evaluated by healthcare professionals to ensure that bilirubin levels return to normal and to rule out any serious conditions. The other options do not relate to increased bilirubin levels: hernias involve tissue protruding through an opening in the abdominal cavity, syphilis is a sexually transmitted infection, and croup is a respiratory condition characterized by a barking cough. Thus, jaundice is distinctly tied to elevated bilirubin levels and is the correct answer.