A long belly button (known as an umbilical hernia) is usually nothing to worry about; most umbilical hernias resolve on their own by the time a baby turns 2. Here's what causes it: Before a baby is born the two muscles lining his abdominal wall (the rectus abdominus muscles) are separated to make room for the umbilical cord to pass into the belly. Once the umbilical cord is cut, the space it once occupied is no longer necessary and so the muscles come together. However in some cases (possibly in as many as one in six infants -- preemies and low birth weight babies are most vulnerable) the muscles don't close and the child's belly button pops out of the now empty space, forming an umbilical hernia.
Some umbilical hernias are visible all the time, while others only bulge out when the child cries, coughs, or strains to poop. It may look alarming when this happens, but know that it doesn't cause your baby any pain. If the hernia doesn't go away on its own, continues to grow, or if rare complications arise (like the protruding tissue becomes trapped outside the body and you're no longer able to push it back in), the hernia can be corrected with a simple surgical procedure. However, if possible, most doctors prefer to wait until a child is older (between 3 and 5) to do the operation, since they're better able to handle general anesthesia then.
Copyright 2009 Meredith Corporation.