Well, it can depend, an umbilical hernia is a pad of fat or part of an abdominal organ protrudes through an incompletly-closed umbilical ring. the tendency for the umbilical ring not to close properly is hereditary in some breeds. some say that they are cause buy the bitch pulling on the cord but this is now largely discredited. A small umbilical hernia is likely to disappear as the puppy gets older. However if a bitch puppy has a large hernia, or one that can be pushed back in with a finder then a vet should be consulted, how old is your pup?