bulging belly button

  My one month old has a bulging belly button. The part that bulges out
  is about the size of a marble. There is no noticeable discoloration,
  and it apparently doesn't cause her any pain (that we can tell). Is this
  normal? It sure does look like something may be wrong with it.
  Thanks for your help...

[HFHS.MD-HSW]

_
Dear Crystal:
A bulging/ballooning out of normally colored skin at the belly button when your baby cries and strains while stooling is characteristic of a benign umbilical hernia. This represents persistence (usually transient) of the opening in the abdominal wall through which oxygen and nutrients were delivered to your baby during the pregnancy while carbon dioxide and other wastes were simultaneously being removed. Umbilical hernias, unlike those which occur in the groin called inguinal hernias, represent no threat to the infant or child. The vast majority close spontaneously by age ten years. In the past, such hernias were covered by tape and other occlusive materials. This is entirely unnecessary and may irritate the skin to boot. If such a hernia fails to close by age ten, a simple surgical procedure will close it and prevent any problems during adolescence or adulthood.
This information is provided for educational purposes only. I trust it will ease concern. Your pediatrician will be fully knowledgeable about this common, usually self-limited condition.
HFHS.MD.HSW
Key Words: Umbilical hernia, inguinal hernia