It’s one of the great unsolved questions of the universe: What gives a baby an innie or an outie?
Well, it’s not really unsolved, but few people know exactly why they have a navel that sticks out or one that is concave. Here’s your answer: “As babies are growing inside the womb, skin grows around the umbilical cord,” says Michael Schoenwetter, M.D., a pediatrician in private practice near Los Angeles and creator of Newborn Care 101, an instructional DVD and website. “Some babies grow more skin, which results in an outie, and some grow less, making an innie.”
The belly button, or navel, is created when the umbilical cord is removed from the newborn. Contrary to conventional wisdom, Schoenwetter says that the way in which the umbilical cord is cut at birth has no bearing on whether a baby will have an innie or an outie. “An outie is just skin that grew around the umbilical cord during development,” he says.
Not surprising, most human babies are born with an innie. Though in some cases, a baby is born with an innie and then appears to develop an outie. This is caused by a minor, usually temporary condition called an umbilical hernia. “An umbilical hernia is an opening of the muscle wall under the belly button,” Schoenwetter says, “and when the baby increases abdominal pressure—such as when she cries—the intestine pushes out [making it look as if the belly button is protruding].” Most umbilical hernias are painless and correct themselves by the age of 4 or 5; however, a very small number of children need to have them surgically repaired.
And get this: While most people consider the type of belly button they have to be of little concern, some uber-conscious grownups have decided that a little corrective surgery is the way to go. Umbilicoplasty, or belly button revision surgery, can make your outie an innie, or can create the “dime-slot” belly button. This is typically is a part of tummy tuck surgery; however, many plastic surgeons will do this procedure separately. Fortunately, Schoenwetter says that in his 15 years in private practice, none of his patient’s parents have requested information on umbilicoplasty for their children.