Birthmarks are coloured marks that are visible on the skin. They’re often present at birth or develop soon afterwards.

There are several different types of birthmark and some of them are very common.

The two main types of birthmark are:

  • vascular birthmarks (often red, purple or pink) caused by abnormal blood vessels in or under the skin
  • pigmented birthmarks (usually brown) caused by clusters of pigment cells

Vascular birthmarks often occur in the head and neck area, mainly on the face. But both types of birthmark can appear anywhere, including inside the body.

If surface blood vessels are affected, a vascular birthmark will appear red, purple or pink. If the affected vessels are deep, the birthmark will appear blue.

Pigmented birthmarks are tan or brown-coloured skin marks.

Vascular birthmarks

Some of the most common types of vascular birthmarks include:

Salmon patch (stork mark)

Pigmented birthmarks

Some of the most common types of pigmented birthmarks include:

Café-au-lait spots

What causes birthmarks?

It’s not fully understood why birthmarks occur, but they’re not usually inherited. Vascular birthmarks are caused by abnormal blood vessels in or under the skin, and pigmented birthmarks are caused by clusters of pigment cells.

Port wine stains are thought to occur because the nerves that control the widening or narrowing of the capillaries (tiny blood vessels) don’t function properly, or there aren’t enough of them. This means that blood is constantly supplied to the skin in that area, which makes it permanently red or purple in colour.

Port wine stains are sometimes related to other conditions, such as Sturge-Weber syndrome and Klippel-Trenaunay syndrome.

Treating birthmarks

Most birthmarks are harmless and don’t need to be treated. Some types of birthmarks will fade over time, whereas other types such as port wine stains will be permanent if they’re not treated.

In some cases, a birthmark will need to be treated for medical reasons – for example, if a haemangioma blocks the airways, affects vision or becomes ulcerated. Some people may also decide to seek treatment for cosmetic reasons.