The human belly button, or navel, is a distinctive abdominal feature, varying in appearance from person to person. This small scar, present on nearly everyone, often sparks curiosity about why some protrude outwards as “outies,” while others are inverted “innies.” These variations result from each individual’s unique healing process.
How Belly Buttons Form
Belly buttons form before birth, when the umbilical cord connects a developing fetus to the placenta. This cord acts as a lifeline, delivering oxygen and nutrients from the mother and removing waste products. Composed of two arteries and one vein, it is essential for fetal growth.
Shortly after birth, the umbilical cord is clamped and cut, leaving a small stump attached to the baby’s abdomen. This stump typically dries out and falls off within one to three weeks. The area then heals, forming the scar that becomes the belly button.
Key Factors Leading to an Outie
The appearance of an outie belly button is primarily influenced by two factors: an umbilical hernia and variations in scar tissue formation. An umbilical hernia occurs when a small portion of the intestine or fatty tissue pushes through a weak spot in the abdominal wall near the navel. This protrusion causes the belly button to bulge outward.
Umbilical hernias are common, especially in newborns, and are often harmless. They typically resolve on their own as the abdominal muscles strengthen, usually by the time a child is one to five years old. The bulge may become more noticeable when the baby cries, coughs, or strains, as this increases pressure within the abdomen.
Variations in how the umbilical cord stump heals and the resulting scar tissue also play a role in whether a navel becomes an outie. The belly button is essentially a scar, and like all scars, its final appearance is subject to individual healing patterns. Sometimes, the skin and scar tissue may protrude outward rather than adhering inward. This can also be influenced by the amount of remaining umbilical skin or tissue after the stump falls off. In some cases, an umbilical granuloma, a small overgrowth of scar tissue, can form at the navel site, contributing to an outie appearance.
Common Misconceptions and Medical Considerations
A common misconception is that the method of cutting or clamping the umbilical cord determines whether a person will have an innie or an outie. However, the shape of the belly button is not influenced by how the cord was cut or cared for.
While outie belly buttons are normal and do not pose health concerns, certain symptoms may indicate a need for medical attention. A healthcare professional should be consulted if the bulge becomes swollen, discolored (red, purple, or dark), or firm to the touch.
Additional signs that warrant medical evaluation include pain or tenderness around the belly button, or symptoms of obstruction such as vomiting or an inability to pass gas or stool. These symptoms, although rare, could suggest that the hernia has become trapped or is affecting blood flow, requiring prompt attention.