Definition of Umbilical hernia:

An umbilical hernia is an outward bulging (protrusion) of the abdominal lining or part of the abdominal organ(s) through the area around the belly button.

Causes, incidence, and risk factors:

An umbilical hernia in an infant occurs when the muscle through which blood vessels pass to feed the developing fetus doesn't close completely.

Umbilical hernias are common in infants. They occur slightly more often in African Americans. Most umbilical hernias are not related to disease. However, umbilical hernias can be associated with rare conditions such as mucopolysaccharide storage diseases, Beckwith-Wiedemann syndrome, and Down syndrome.