Our belly button, a small mark on our abdomen, is a universal human feature that often sparks curiosity. This unique indentation or protrusion is present on almost everyone, yet its origin and purpose are not widely understood.
The Umbilical Cord: Our First Connection
Before birth, a fetus relies on the umbilical cord for sustenance and waste removal. This structure connects the fetus to the placenta, forming a vital lifeline within the womb. The umbilical cord typically contains two umbilical arteries and one umbilical vein, encased within a protective, gelatinous substance called Wharton’s jelly.
The single umbilical vein transports oxygen-rich blood and essential nutrients from the mother’s placenta to the fetus. Conversely, the two umbilical arteries carry deoxygenated blood and waste products from the fetus back to the placenta, where they are processed by the mother’s body. This intricate system ensures continuous support for the growing baby throughout gestation.
From Cord to Navel: How It Forms
After birth, the umbilical cord is no longer needed as the baby begins to breathe and feed independently. Healthcare providers clamp and cut the cord, a painless procedure for both mother and baby because it contains no nerves. This leaves a small stump attached to the newborn’s abdomen.
The umbilical stump undergoes a natural drying process, gradually shriveling and changing color from yellowish to brown or black. This stump typically detaches within one to three weeks after birth, although it can sometimes take up to 21 days. Once the stump falls off, the skin heals, forming the scar we recognize as the belly button.
A Lifelong Remnant: Purpose and Appearance
The navel serves no physiological purpose after birth. It is a permanent scar, marking the location where the umbilical cord once connected an individual to their mother. The appearance of belly buttons can vary significantly from person to person.
These variations, commonly referred to as “innies” (an inward depression) or “outies” (an outward protrusion), are determined by how the scar tissue heals. The way the umbilical cord was clamped or cut does not influence whether someone develops an innie or an outie. Innies are more common, accounting for approximately 90% of individuals. An “outie” can also be caused by minor conditions like an umbilical hernia or granuloma, or temporarily by increased abdominal pressure during pregnancy.