What is a birthmark?

A birthmark is any mark on a child's skin which is present when they are born, or which develops soon after birth. Some birthmarks are internal and not easily seen so they may only be diagnosed through further investigation.

It's not uncommon for babies to be born with birthmarks. Most of the time, birthmarks are harmless and some even go away as the child grows. However, a small number of birthmarks may have complications or be a sign of a certain disease or condition. In this case, further investigation may be recommended.

Birthmarks can be present anywhere on the face or body and vary in shape, colour and size. It's not really understood what causes birthmarks, and they are not caused by genetics. However, in some families, birthmarks are more common and can appear in the same place on the body. Many birthmarks fade over time, though some may be permanent and may get larger as the child ages.

Will all babies have a birthmark?

Although birthmarks are common, not all babies will have them. Some birthmarks are more obvious than others, or in places where they can be more easily seen.

What are the different types of birthmarks?

Most birthmarks can be divided into two different types:

Vascular birthmarks — these involve blood vessels which are clustered in one area, or where the blood vessels are larger than normal. Vascular birthmarks affect around 40% of newborns and are often categorised according to how large they are.

Pigmented birthmarks — these happen when there is more pigment concentrated in one part of the skin than in the rest of the skin.

What causes birthmarks?

It's not clearly understood why birthmarks occur. Vascular birthmarks are caused by abnormal blood vessels in or under the skin. Pigmented birthmarks are caused by clusters of pigment cells. Port wine birthmarks occur because there are changes to the nerve endings controlling the opening and closing of small blood vessels which supply the skin.

Common types of vascular birthmarks in babies

Stork marks or salmon patch — these may be flat or raised areas of red or pink skin. They are commonly seen on the baby's face, back of their neck or head. Treatment is not usually needed and most disappear on their own after a few years. They got their name because of the folklore of babies being brought by storks, and the mark on the baby's skin is from the stork's beak.

Infantile hemangioma or a strawberry birthmark — 1 in 15 babies will develop a hemangioma shortly after birth. Girls and premature babies are more commonly affected by infantile hemangiomas. In most cases, there is no need for treatment, and many hemangiomas will shrink or disappear on their own over time. If the hemangioma is large or causing problems, treatment may be recommended.

Port wine stains — these are the colour of port wine and appear as a pink-reddish or purple mark, most commonly on the baby's face or elsewhere on their body. Port wine stains are permanent and tend not to fade. Treatment may be recommended since they often grow as the child grows and can become darker over time.

Common types of pigmented birthmarks in babies

Mongolian spots — also called congenital dermal melanocytosis. These are flat blue/grey spots with an irregular shape. They are commonly found on the baby's bottom or lower back. They can sometimes be mistaken for a bruise. Babies with Indigenous, Pacific Islander and Asian heritage are more likely to have Mongolian spots. Generally, this type of birthmark fades in early childhood. Treatment is not usually needed, and these birthmarks usually fade completely over time.

Café-au-lait spots — these are flat, coffee-coloured areas on the skin which are often scattered on the shoulders and back. It's common to have 1 or 2 café au lait spots though 6 or more can be a sign of the condition called neurofibromatosis and may need further investigation.

Congenital melanocytic naevi (CMN) — these are skin lesions which are present at, or shortly after, birth. They are typically brown or black although their colour may change over time. They often look like common moles but may be larger and more raised. In a very small number of cases, this may be associated with rare complications and need further investigation.

Is treatment needed for birthmarks?

Most of the time, birthmarks are harmless and don't need to be removed. But if they are large or there is a risk of them growing and causing concern, treatment may be recommended. Treatment is often advised if a birthmark is affecting vision or breathing. It may also be recommended if there is a potential for psychological effects from teasing and the child being self-conscious.

Laser is the most common type of treatment for birthmarks that are brown/black and vascular lesions caused by abnormal blood vessels.

Medication which is used to lower blood pressure or inflammation can reduce the amount of blood flow to vascular birthmarks. Less frequently, surgery is done to remove a loose sac of tissue or fatty deposits which remain on the skin once the birthmark has been treated. This is often recommended if it is growing over the child's eye or one side of their nose.

Because of the varied types of birthmarks and treatment options available, it is always best to speak to your doctor about any birthmarks you may notice at birth or over time.