The belly button (navel) marks our earliest connection to our mothers, where the umbilical cord once attached, providing essential nourishment during development. While most people have an “innie,” where the skin forms a depression, some have an “outie,” characterized by a protrusion of tissue. Both forms are natural variations in human anatomy.
The Umbilical Cord and Belly Button Formation
During pregnancy, the umbilical cord acts as a lifeline, transporting oxygen and nutrients from the mother’s placenta to the developing fetus and carrying waste products away. After birth, the umbilical cord is no longer needed and is clamped and cut, leaving a small stump attached to the newborn’s abdomen.
Over the next one to three weeks, this umbilical stump gradually dries, shrivels, and darkens before detaching naturally, similar to how a scab falls off a healed wound. The remaining area then forms the belly button, which is essentially a scar. The final appearance of the navel, whether it becomes an innie or an outie, is primarily determined by the unique way the skin and underlying tissues heal and scar around this site. This healing process is largely a matter of chance and is not influenced by how the umbilical cord was cut or cared for post-birth.
Prevalence of Outie Belly Buttons
Approximately 10% of the population has an outie navel, while the vast majority, around 90%, have an innie. This variation is simply a natural part of human diversity, much like differences in hair color or eye shape. It does not signify any underlying health implications in most cases. It is generally considered a minor anatomical difference without medical significance.
Understanding Outie Belly Buttons
Most outie belly buttons are a harmless cosmetic variation resulting from the natural healing of the umbilical cord stump. The way scar tissue forms, or slight structural differences in the abdominal wall, can lead to the skin protruding slightly rather than forming an indentation.
Sometimes, an outie appearance can be linked to specific, typically minor, medical conditions. An umbilical hernia, where a small portion of the intestine or fatty tissue bulges through a weak spot in the abdominal wall near the navel, can cause a prominent belly button. These hernias are common in infants, affecting about 20% of newborns, and frequently close on their own by the age of four or five.
Another reason can be an umbilical granuloma, which is a small, moist, reddish lump of tissue that forms after the cord falls off. These also typically resolve with minimal intervention. Other situations, such as pregnancy, can temporarily cause an innie to become an outie due to increased abdominal pressure, usually reverting after childbirth.
While outies are generally not a concern, consulting a doctor is advisable if there is pain, discoloration, a rapidly changing appearance, or signs of infection around the navel.