What Causes an Outie Belly Button and When to See a Doctor?

An outie belly button is a small protrusion of skin and scar tissue at the navel, and it has nothing to do with how your umbilical cord was cut. About 10 percent of people have one, and the shape is determined by how tissue heals after the cord stump falls off, sometimes compounded by an underlying umbilical hernia. In most cases an outie is purely cosmetic, though certain conditions can change the navel’s appearance and deserve medical attention.

How the Belly Button Actually Forms

Every belly button is a scar. After birth, the remaining stump of the umbilical cord dries out, shrivels, turns dark, and drops off on its own, typically between five and fifteen days after delivery.¹ Once the stump separates, the opening heals inward and the skin contracts around it. Whether you end up with an innie or an outie depends on how the underlying tissue knits together during that healing phase. A bit of extra scar tissue, a slightly different attachment to the abdominal wall, or a small pocket of fatty tissue beneath the skin can push the center of the navel outward instead of letting it sink in.

The persistent myth that a doctor or midwife “tied the cord wrong” or “cut it too long” refuses to die, but it has no anatomical basis. The clamp is placed well away from the baby’s body, and the stump that remains is the same length regardless of technique. The shape of the scar is governed by the baby’s own healing biology, not by anything that happens in the delivery room.

Umbilical Hernias and the Outies They Create

The single most common reason a baby develops a prominent outie is an umbilical hernia. During fetal development, the muscles of the abdominal wall close around the spot where the cord passes through. When that ring of muscle does not shut completely, a small loop of intestine or a pad of fatty tissue can push through the gap, creating a soft bulge right at the navel. This is the classic outie that puffs out when a baby cries or strains.

Umbilical hernias are extremely common in infants. A study examining children across different age groups in Africa found hernias present in roughly 23 percent of the youngest group surveyed, dropping to about 8 percent in older children, with spontaneous closure continuing up through age fourteen.² The rates vary by population and how hernia is defined, but the overall pattern is consistent: most pediatric umbilical hernias close on their own as the abdominal wall strengthens during childhood. Surgery is typically reserved for hernias that persist past age four or five, grow larger over time, or cause pain. If you have an outie as an adult and it has always been soft, painless, and the same size, there is a reasonable chance a small hernia closed during childhood but left the extra skin behind.

When a Bump Is Not a Hernia

Not every protruding navel involves a gap in the muscle wall. Several other conditions can make a belly button stick out, and they require different approaches.

Umbilical Granulomas

After the cord stump falls off, a small lump of moist, pinkish tissue sometimes forms at the base of the navel. This is called an umbilical granuloma, and it is one of the most common minor complications in newborns. The granuloma is not dangerous, but it can ooze a small amount of clear or slightly yellowish fluid, which understandably alarms new parents. Treatment is straightforward. A randomized trial comparing common table salt applied to the granuloma against silver nitrate cauterization found that both methods resolved the problem in the majority of cases, with the salt approach working in about 86 percent and silver nitrate in about 65 percent.³ Neither method caused major side effects. The granuloma itself does not produce a permanent outie; once treated, the navel heals normally.

Urachal Remnants

The urachus is a small tube that connects the bladder to the umbilicus during fetal life. It normally seals shut before birth, but occasionally a portion of it stays open. A patent urachal sinus is an outpouching structure just beneath the navel that can accumulate debris, become infected, or even form small stones.⁴ This is uncommon, but it can present as a bump, drainage, or recurrent redness at the navel in children or even healthy adults. When a belly button that was previously normal starts oozing or swelling, a urachal remnant is one of the possibilities a doctor will consider.

What Should Prompt a Doctor Visit

Most outies are harmless and need no treatment at all. That said, certain changes in a belly button’s appearance or behavior warrant a closer look.

New bulging: An adult who develops a new outie or a bulge at the navel may have an umbilical hernia that developed later in life, often related to pregnancy, weight gain, or heavy lifting. Adult hernias are less likely to close on their own and sometimes need surgical repair.
Pain or tenderness: A hernia that becomes painful could be incarcerated, meaning tissue is trapped in the gap. This is uncommon but needs urgent attention because it can cut off blood supply to the trapped tissue.
Persistent discharge: Fluid, blood, or pus coming from the navel in an adult could point to a urachal remnant, an infection, or a cyst.
A firm, growing nodule: Any hard lump at the navel that was not there before should be evaluated. The differential diagnosis for an umbilical nodule includes benign possibilities like keloids, sebaceous cysts, and granulomas, but it also includes rarer concerns such as endometriosis presenting at the navel, or even malignancies like nodular melanoma or a metastatic deposit sometimes called a Sister Mary Joseph nodule.⁵

The takeaway is simple: a lifelong, stable, painless outie is almost certainly fine. A belly button that changes is worth getting checked.

Umbilicoplasty and Cosmetic Reshaping

For people who dislike the look of their outie, surgery to reshape the navel exists and has been documented in the plastic surgery literature for decades. The procedure, called umbilicoplasty, involves excising the excess scar tissue that forms the outie’s protrusion and using small skin flaps to reconstruct the navel into a concave, hooded shape that mimics a natural innie.⁶ A classification of different umbilicoplasty procedures has been published to help surgeons match technique to the specific type of protrusion a patient presents with.⁷

Umbilicoplasty is sometimes performed as a standalone cosmetic operation and sometimes bundled with an abdominoplasty, commonly known as a tummy tuck. In a tummy tuck, the surgeon already repositions the navel on the tightened abdominal wall, so reshaping it at the same time is a natural addition. As a standalone procedure, umbilicoplasty is usually done under local anesthesia and takes under an hour. Recovery involves keeping the area clean and avoiding strain on the abdominal muscles for a few weeks. Scarring is generally confined to the inside of the navel, where it is hidden.

A few things to keep in mind if you are considering it. First, the navel’s shape can change again with significant weight fluctuations or pregnancy, so timing matters. Second, there is no medical reason to convert an outie to an innie. The motivation is entirely cosmetic. Third, as with any elective surgery, complications like infection, poor scarring, or asymmetry are possible, even if they are uncommon in experienced hands.

Why Outies Are Not Genetic in the Way People Assume

You will sometimes hear that outie belly buttons “run in families,” and there is a kernel of truth buried in the claim, but it is not as straightforward as inheriting eye color. No single gene has been identified that dictates innie versus outie. What can run in families is the tendency toward umbilical hernia. If the connective tissue around the umbilical ring is genetically a bit weaker in a particular family line, more members of that family may develop small hernias in infancy, which can produce outies. But the actual shape of the healed scar also depends on wound-healing characteristics, skin elasticity, and the amount of subcutaneous fat around the navel, all of which vary between individuals even within the same family.

So the honest answer to “is an outie genetic?” is: the predisposition to some of its causes can be inherited, but the belly button itself is a scar, and scars are not directly encoded in your DNA. Two siblings born to the same parents, delivered by the same doctor, can easily end up with different navel shapes.

Outies During Pregnancy

If you had an innie your entire life and it suddenly popped outward during pregnancy, you are in good company. As the uterus expands, it pushes the abdominal wall forward and the tissue behind the navel gets pressed from behind. In many pregnant people, the increased intra-abdominal pressure is enough to evert the navel entirely, turning it into a temporary outie. This is not a hernia in most cases, just the mechanical effect of a growing uterus displacing the tissue. The navel usually returns to its previous shape within a few months after delivery, though it may not look exactly the same as before, especially after multiple pregnancies.

That said, pregnancy can also unmask or worsen a true umbilical hernia. If the bulge is large, painful, or does not flatten when you lie on your back, mention it at a prenatal visit. Most pregnancy-related umbilical hernias are watched rather than repaired until after delivery, unless symptoms become severe.

Cleaning an Outie

Innies tend to collect lint, dead skin, and bacteria in their folds, and most hygiene advice focuses on keeping that cavity clean. Outies have a different profile. Because the navel protrudes, there is less of a pocket for debris to accumulate, but the folds at the base of the protrusion can still harbor moisture and bacteria. If you notice redness, an odor, or irritation around an outie, gentle cleaning with warm water and mild soap is usually all that is needed. Avoid using alcohol or hydrogen peroxide inside the navel, as these can irritate the delicate skin and slow healing if there is any minor abrasion.

For newborns with a protruding navel, the best care is the simplest: keep the area dry, let air circulate, and do not cover the stump or the healing navel with tight dressings or belly bands. The old practice of taping a coin over the outie to “push it in” has no medical support and can actually increase the risk of skin irritation or infection.

How People Feel About Their Belly Buttons

Belly button shape might seem trivial, but it is one of those body features that people develop surprisingly strong feelings about, especially during adolescence. Researchers developing a validated patient satisfaction scale for belly button appearance included “the type of belly button you have (e.g., innie or outie)” as a specific item evaluated during patient interviews about appearance and satisfaction.⁸ The fact that a formal psychometric tool was developed for navel satisfaction tells you something about how much the feature matters to people seeking body contouring procedures.

In everyday life, outie belly buttons show more visibly through tight clothing, which can cause self-consciousness. Online forums and social media are full of people asking whether their outie is “normal.” It is worth stating plainly: having an outie is a normal anatomical variant, not a defect or a sign that something went wrong during your birth. The ratio of innies to outies in any given population is lopsided, which means outies are in the minority, but minority and abnormal are not the same thing. If your outie does not hurt and has not changed, it is simply the scar your body chose to make.

Belly Buttons Across Species

Humans are not the only mammals with belly buttons. Any placental mammal that developed inside a uterus, nourished by an umbilical cord, will have some version of a navel scar. In large mammals like dolphins, orangutans, and whales, the scar is visible to the naked eye. In smaller animals like dogs and cats, it tends to be a faint, flat mark hidden under fur. Marsupials and egg-laying mammals do not have a traditional belly button because their developmental process does not involve the same kind of cord. The human navel is unusually prominent compared to other species, partly because we lack the fur that would conceal it and partly because our upright posture and relatively sparse body hair put it on permanent display. Whether that scar ends up concave or convex is, as far as anyone can tell, a uniquely human concern.