Birthmarks are an area of pigmented or raised skin that can be present at birth or appear shortly afterward. There are many different types of birthmarks, and most of them are harmless.

While birthmarks are common, not everyone has them. So exactly how frequently do birthmarks occur? And why exactly do we get them? Keep reading to find out the answers to these questions and more below.

Birthmarks are quite common. In fact, it’s estimated that more than 10 percent of babies have some sort of birthmark.

Some types of birthmarks appear more frequently than others. For example, vascular birthmarks like hemangiomas occur in 5 to 10 percent of newborns. A stork mark is another common type of vascular birthmark.

Other birthmarks occur less often. Port-wine stains are rather rare, with an estimated incidence of 0.3 percent.

Many birthmarks will fit into one of the categories noted below:

  • Vascular birthmarks. These birthmarks are associated with blood vessels under the skin and are typically red or pink.
  • Pigmented birthmarks. This category of birthmark occurs due to pigment changes within the skin. These types of birthmarks can be brown, black, or bluish.

There are different types of birthmarks within each category. Let’s look at some examples.

Vascular birthmarks

The types of vascular birthmarks can include:

  • Hemangiomas. When this type of birthmark occurs near the skin’s surface, it’s pink or red, and can occur on the face or neck. It often appears as a raised lump and begins to grow in the months following birth. Many hemangiomas eventually shrink.
  • Stork marks (salmon patches). Stork marks are flat and are pink or red. They most often occur on the face and the back of the neck, and can be more apparent when a baby is crying or straining. They may fade with time.
  • Port-wine stains. Port-wine stains can range from pink to purple and may darken, get larger, or become lumpier as a child gets older. They often occur on the face. Port-wine stains are permanent.

Pigmented birthmarks

Some of the types of pigmented birthmarks are:

  • Café au lait spots. These are flat areas of skin that are darker than the surrounding area, typically being tan or brown. Café au lait spots can occur anywhere on the body. Like port-wine stains, they’re generally permanent.
  • Mongolian spots. Mongolian spots are grayish blue and are often mistaken for bruising. They’re most common around the buttocks and the lower back. Most Mongolian spots tend to fade over time.
  • Congenital moles. These are brown moles that are present at birth. They may be flat or slightly raised and can appear anywhere on the body. Most of the time, they’re permanent.

Why exactly birthmarks form isn’t completely understood. However, we do have a general understanding of the causes of the above two categories of birthmarks.

Vascular birthmarks form when blood vessels that are present in or below the skin don’t develop properly. This is what gives them their pink or red coloration.

Pigmented birthmarks happen due to an increase in darker pigmentation of the skin. This can be due to an increase in pigment (melanin) in the area or the clumping of melanin-producing cells called melanocytes.

Most types of birthmarks aren’t hereditary. That means that you typically don’t inherit them from your parents. However, there are some cases where certain birthmarks may be due to a genetic defect, and it may or may not run in your family.

Some types of birthmarks are associated with rare genetic conditions. These can include:

  • Neurofibromatosis type 1 (NF1). Having a large number of café au lait spots is associated with this condition. People with NF1 have a higher risk of getting tumors affecting the nerves and skin. NF1 is inherited.
  • Sturge-Weber syndrome. Port-wine stains are associated with this condition. Sturge-Weber syndrome can lead to stroke-like episodes and glaucoma. It’s not inherited.
  • Klippel-Trenaunay syndrome. Port-wine stains are also associated with this condition. Klippel-Trenaunay syndrome causes an overgrowth of bones and other tissues that can lead to pain and restriction of movement. It’s not thought to be inherited.

So what does it mean if you don’t have a birthmark? Not much. While birthmarks are common, not everyone has one.

There’s no way to predict if a child will have a birthmark or not. Not having a birthmark isn’t a sign of a particular health condition or a cause for concern.

Also, remember that many types of birthmarks fade as children get older. You may have had a birthmark when you were very young but it has since disappeared.

Most birthmarks are harmless. However, in some cases, they may develop into cancer.

Children that are born with a congenital mole are at an increased risk of developing a melanoma type of skin cancer when they’re older.

If your child has multiple congenital moles or a larger congenital mole, it’s important that a dermatologist regularly evaluates the affected skin for changes.

Some birthmarks may affect self-esteem, particularly when they’re in a very visible area like the face. Others may affect the function of a specific part of the body, such as a hemangioma located near the eyes or mouth.

In general, most birthmarks are left alone. However, there are some potential options for reducing or removing birthmarks. These can include:

  • Medications. Topical medications can be used to prevent or slow the growth of hemangiomas. This may be recommended when hemangiomas are large, fast-growing, or disruptive to another area of the body.
  • Laser therapy. Laser therapy can be used to help lighten or reduce the size of some birthmarks, such as port-wine stains.
  • Surgery. Surgery may be recommended to remove some birthmarks. Examples include congenital moles that may become cancerous and large, raised birthmarks that affect appearance. Surgical removal of birthmarks can result in scarring.

Birthmarks are colored or raised areas of skin. They can either be present at birth or appear in the time shortly after birth.

Birthmarks are common. However, while many children have some sort of birthmark, others don’t. Additionally, birthmarks typically don’t run in families.

Many birthmarks are harmless, but some, such as congenital moles, can potentially become cancerous. Others, such as port-wine stains and numerous café au lait spots, can be associated with rare genetic conditions.

Regardless of the type, it’s important that a doctor evaluates all birthmarks. While most birthmarks can be left alone, others may require closer monitoring or treatment.