Every human possesses a belly button, also known as the navel or umbilicus. This feature marks a significant biological event from the earliest stages of life. While its appearance varies, the belly button is essentially a scar, a permanent reminder of the vital connection that sustained life before birth. Its existence stems directly from fetal development and the transition to independent life.
The Umbilical Cord’s Vital Function
During pregnancy, the umbilical cord connects a developing fetus to the placenta within the mother’s uterus. This flexible, tube-like structure facilitates the exchange of essential substances. The umbilical cord contains three blood vessels: one umbilical vein carries oxygen-rich, nutrient-filled blood from the placenta to the fetus, and two umbilical arteries transport oxygen-poor blood and waste products back to the placenta.
The placenta acts as a temporary organ, functioning as the fetus’s lungs, kidneys, and gastrointestinal system. It allows for the transfer of oxygen and nutrients while removing carbon dioxide and other waste, without directly mixing maternal and fetal blood. This two-way exchange ensures the fetus receives everything necessary for growth and development throughout gestation.
The Navel’s Formation
The belly button forms after birth, when the umbilical cord is clamped and cut. This procedure is painless for both mother and baby because the cord contains no nerve endings. A small segment, known as the umbilical stump, remains attached to the baby’s abdomen.
Over one to three weeks, this stump naturally dries, shrivels, and changes color before detaching on its own, much like a scab. The healing process leaves behind the belly button, a scar marking the cord’s former attachment point. Once the stump falls off and the area heals, the belly button has no further physiological function.
Common Navel Questions
One frequent question about belly buttons concerns the distinction between “innies” and “outies.” Whether a person has an inward-facing (innie) or outward-protruding (outie) navel is determined by how the scar tissue heals after the umbilical stump falls off. Innies are more common, accounting for approximately 90% of individuals.
Sometimes, an outie can be due to a small umbilical hernia, where a portion of the intestine or abdominal fat pushes through a weakness in the abdominal muscles near the navel. These hernias are generally harmless and often close on their own as the child grows. Another common curiosity is belly button lint, a collection of clothing fibers, dead skin cells, and sweat that accumulates in the navel, especially in innies due to their concave shape. Regularly cleaning the belly button with soap and water helps prevent odor or accumulation.