Belly buttons are the scar left behind from your umbilical cord, which was your entire life support system before birth. During pregnancy, the umbilical cord connected you to your mother’s placenta, delivering every bit of oxygen, nutrition, and energy your developing body needed. Once you were born and could breathe and eat on your own, the cord was clamped and cut, and the small stump that remained dried up and fell off, leaving the navel you see today.
What the Umbilical Cord Actually Does
Before birth, a fetus can’t breathe, eat, or get rid of waste on its own. The umbilical cord handles all three jobs. Oxygen and nutrients from the mother’s blood cross the placenta and travel through the cord’s blood vessels into the baby’s circulation, where they’re distributed to every organ and tissue. At the same time, carbon dioxide and waste products flow back through the cord in the opposite direction, returning to the mother’s bloodstream so her body can eliminate them.
This two-way exchange is constant throughout pregnancy. The cord is essentially a bundle of blood vessels surrounded by a protective jelly-like coating. One vein carries oxygen-rich blood from the placenta to the baby, while two arteries carry depleted blood and waste back to the placenta. That single vein supplies everything the fetus needs to grow from a cluster of cells into a full-term baby over roughly 40 weeks.
What Happens After Birth
Once a baby is born and takes its first breaths, the lungs take over the job of delivering oxygen. The digestive system starts processing milk. The umbilical cord, no longer needed, is clamped and cut a few inches from the baby’s abdomen. The short stump that remains dries out, darkens, and falls off on its own, typically within about three weeks. What’s left underneath is the belly button.
The navel is a true scar. The skin simply healed over the spot where the cord was once attached. It has no ongoing biological function in your body after that point.
Why Some Are Innies and Others Are Outies
About 90% of people have an innie (a concave belly button), while roughly 10% have an outie (one that pokes outward). Despite a common belief, the shape has nothing to do with how the doctor cut or clamped the cord. Outies are mostly a matter of genetics, the same way dimples or curly hair are. When the tiny remnant of the cord sticks out past the surrounding skin as it heals, the result is an outie.
In some cases, an outie is caused by a small umbilical hernia, where a bit of tissue pushes through the abdominal wall near the navel. Most umbilical hernias in babies close on their own within a few years. Pregnancy can also temporarily turn an innie into an outie, as the growing uterus pushes the abdominal wall forward and stretches the navel outward. It usually returns to its original shape after delivery.
The Hidden Connection to Your Bladder
If you’ve ever poked your belly button and felt a strange sensation lower in your abdomen, or even a mild urge to pee, there’s a real anatomical reason. During fetal development, a structure called the urachus connects the top of the forming bladder to the umbilical cord. This canal typically closes and dissolves before birth, but it leaves behind a fibrous band running from the navel down to the bladder. That remnant, along with the nerves lining the abdominal wall in that area, is why pressing on your belly button can produce that odd tingling feeling deep in your pelvis.
In rare cases, the urachus doesn’t fully close, which can lead to issues like cysts or drainage from the belly button. These are uncommon and usually diagnosed in infancy or early childhood, though they occasionally show up in adults.
Keeping Your Belly Button Clean
Because innies are concave and sometimes surprisingly deep, they can trap dead skin cells, skin oils, lint from clothing, and dirt. If this debris isn’t cleaned out regularly, it can clump together and harden over time into what’s called a navel stone. These stones can grow large enough to become visible and may cause irritation or odor.
Prevention is simple: wash your belly button with soap and water when you shower, and if yours is particularly deep, use a cotton swab to gently clean inside it. This is especially worth noting for caregivers of elderly or disabled people, who may not be able to clean the area themselves. A navel stone isn’t dangerous, but it’s easily avoided with basic hygiene.