The belly button, or umbilicus, is the scar left behind after the umbilical cord is detached at birth. Far from being a static landmark, the navel is a dynamic structure that responds to internal and external changes the body undergoes across a lifetime. Belly buttons change, altering their shape, depth, and even orientation in response to various life events and biological processes.
The Anatomy That Allows for Change
The navel’s ability to change stems from its distinct anatomical structure. The umbilicus is essentially a stalk of scar tissue where the skin is tethered directly to the abdominal fascia, a tough layer of connective tissue covering the underlying muscles. This connection occurs at the midline, where the two major abdominal muscles meet. Unlike the rest of the abdomen, the belly button area lacks the support of muscle or bone directly beneath the skin, making it a point of relative weakness. The appearance of the navel—whether it is an “innie” or an “outie”—is largely determined by the amount of subcutaneous fat and how the umbilical cord stump healed initially. Because the skin is tethered to the fascia, it is sensitive to fluctuations in internal pressure and the stretching or relaxing of the surrounding skin.
Transformations During Major Life Events
Significant physiological shifts often result in noticeable, though frequently temporary, changes to the navel’s appearance. Pregnancy is one of the most common causes of dramatic navel alteration, particularly during the second and third trimesters. As the uterus expands to accommodate the growing fetus, it exerts outward pressure on the abdominal wall.
This internal pressure pushes the navel forward, which can cause a typical “innie” to flatten out or temporarily protrude, becoming an “outie.” This physical change is harmless and is simply a result of the skin being stretched taut over the growing abdomen. Following delivery, as the abdominal wall and skin return to their pre-pregnancy state, the navel usually reverts to its original shape.
Changes in body weight also affect the navel’s contour due to the accumulation or reduction of subcutaneous fat. With significant weight gain, the surrounding abdominal skin stretches, often causing the navel to appear deeper and wider as it becomes surrounded by more tissue. Conversely, rapid weight loss can leave behind excess, lax skin that lacks the elasticity to snap back into place. This can result in a navel that appears saggy, stretched, or elongated, caused by the depletion and remodeling of dermal collagen fibers.
Permanent Alterations and Medical Causes
Some changes to the umbilicus are more permanent, resulting from the cumulative effects of aging, medical conditions, or surgical intervention. One of the most gradual but lasting shifts is caused by the natural aging process. Over decades, the skin loses collagen and elastin, the proteins responsible for firmness and elasticity. This reduction causes the skin surrounding the navel to become less taut, leading to a general drooping or flattening of the area.
A more abrupt change is the development of an umbilical hernia, which alters the navel’s shape and contour. A hernia occurs when a portion of the intestine or abdominal tissue protrudes through a weak spot in the abdominal wall near the navel, creating a visible bulge or lump.
Surgical procedures, such as abdominoplasty, permanently reshape the navel. During a full tummy tuck, the surrounding skin and fat are pulled downward and tightened, while the navel’s internal stalk remains attached to the abdominal wall in its original location. The surgeon then creates a new opening in the repositioned skin to bring the navel through, resulting in a resculpted and often more vertically-oriented appearance.