While they are often much smaller than Inguinal Hernias, Umbilical Hernias represent a more ominous threat because of the immediate presence of loops of intestine in the area, and the higher risk of incarceration from the smaller defect surrounded by tough aponeurotic tissue and fascia.  These are common in small children, and also in some women following pregnancy.  They represent a congenital defect that has been exacerbated by intraabdominal stress, pressure or mass effect.