Umbilical hernias are caused by a weakness in the ring of muscles that surround the belly button. Because of this weakness, abdominal fluid or intestinal contents can push on the skin covering the belly button causing a bulge. The bulge will be more noticeable if a baby is crying or if an older child is standing up.
Umbilical hernias are common and not serious. In the past, parents were told to bind the hernia so it would go away. This does not work and may create a rash on the baby’s abdomen. Fortunately, most resolve on their own by the time children start first grade. If they persist beyond this point, they may need to be repaired surgically.
Umbilical hernias rarely cause harm. Once in my 30-year career, a piece of intestinal fat got “stuck” in the hernia ring had to be fixed on an emergency basis. The way I knew something was wrong was because the area was red and the baby was crying. When I pressed on the hernia, instead of being easily pushed back in, it was hard and tender to touch.