The belly button, or navel, is a distinct feature found on the abdomen of nearly all placental mammals, including humans. This indentation or protrusion is a permanent reminder of a crucial connection that existed before birth. It prompts curiosity about its origins and any potential ongoing purpose.
The Umbilical Cord’s Essential Role
Before birth, the umbilical cord serves as a vital lifeline, connecting a developing fetus to the placenta within the mother’s uterus. This structure facilitates a continuous exchange of essential substances. It contains one vein, delivering oxygen and nutrient-rich blood from the placenta to the fetus, and two arteries that return deoxygenated, waste-laden blood from the fetus back to the placenta.
The placenta, a temporary organ, functions as the fetus’s lungs, kidneys, and gastrointestinal system, managing gas exchange, waste removal, and nutrient absorption. Through the umbilical cord, the fetus receives all necessary oxygen, glucose, and other nutrients for growth and development. This system ensures the fetus thrives.
From Lifeline to Landmark: How Your Belly Button Forms
At birth, the umbilical cord, having completed its life-sustaining role, is no longer needed. Healthcare providers typically clamp and cut the cord, a painless procedure. The remaining segment attached to the baby, known as the umbilical stump, then begins a natural drying process.
Over one to three weeks, the stump gradually shrivels, changes color, and eventually detaches on its own. This natural process leaves behind the scar tissue that forms the belly button, determining its final appearance.
The Belly Button’s Life After Birth
After the umbilical stump falls off and heals, the belly button serves no functional purpose. It is a vestigial scar, a mark of our prenatal development. The appearance of a belly button can vary widely, often categorized as either an “innie” (concave) or an “outie” (protruding).
These variations are determined by factors such as the amount of scar tissue that forms, how the skin heals, and the underlying abdominal wall structure, rather than how the umbilical cord was cut or clamped. For example, an “outie” can sometimes occur due to extra scar tissue or, in some cases, a minor umbilical hernia where abdominal tissue slightly protrudes. While most people have “innies,” “outies” are a normal variation, accounting for about 10% of the population.