The belly button, also known as the navel or umbilicus, is a common feature on the abdomen of humans and other placental mammals. It appears as a small depression or sometimes a slight protrusion on the body’s surface. It is universally present in individuals who developed inside a mother’s womb.
The Umbilical Cord’s Purpose Before Birth
Before birth, the umbilical cord connects a developing fetus to the mother’s placenta. This flexible, tube-like structure facilitates the exchange of necessary substances for growth. The umbilical cord contains two arteries and one vein, all encased within a protective gelatinous substance called Wharton’s jelly.
The umbilical vein carries oxygen-rich and nutrient-filled blood from the placenta to the fetus. Conversely, the two umbilical arteries transport deoxygenated blood and waste products, such as carbon dioxide and urea, from the fetus back to the placenta.
The Belly Button After Birth
Once a baby is born, the umbilical cord is no longer needed, as the newborn can now breathe and feed independently. Healthcare providers clamp and cut the cord, a painless procedure due to the absence of nerves in the cord. This leaves a small stump attached to the baby’s belly.
The remaining umbilical stump dries, shrinks, and darkens over one to three weeks before falling off. The spot where the cord was attached then heals, forming the belly button. The belly button itself, as a physical feature, does not have a direct physiological function; it is essentially a scar or a remnant of this past connection.
Why Belly Buttons Look Different
The appearance of a belly button, whether an “innie” (concave) or an “outie” (protruding), is determined by how the umbilical cord stump heals and scars. This process is a matter of chance and is not influenced by how the cord was cut or clamped. Most people have an innie belly button.
Factors influencing the final shape include excess skin, scar tissue formation, and the underlying structure of the abdominal wall. For example, an outie may form if the remaining cord stump protrudes outward instead of sinking inward during healing. The belly button is a unique scar for each individual. Maintaining hygiene involves cleaning the area gently with water and mild soap, especially for innies, which can collect lint and bacteria.