There are two main types of birthmarks, which have different causes:

• Vascular birthmarks happen when blood vessels don’t form correctly. Either there are too many of them or they’re wider than usual.
• Pigmented birthmarks are caused by an overgrowth of the cells that create pigment (color) in skin.

Vascular Birthmarks

The most common vascular (blood vessel) birthmarks are macular stains, hemangiomas, and port-wine stains:

Macular stains. Also called salmon patches, angel kisses, or stork bites, these faint red marks are the most common type of vascular birthmark. Macular (MA-kyuh-ler) stains typically are on the forehead or eyelids; the back of the neck; or on the nose, upper lip, or back of the head. They may be more noticeable when the baby cries. Most often they fade on their own by the time a child is 1 to 2 years old, although some last into adulthood.

Hemangiomas are superficial when they’re on the surface of the skin (“strawberry marks”), deep when found below the skin’s surface, and compound when they affect both layers. A hemangioma (hee-man-jee-OH-muh) can be slightly raised and bright red, and usually won’t be visible until a few days or weeks after a baby is born. Deep hemangiomas might look bluish because they involve blood vessels in deeper layers of the skin.

Hemangiomas grow quickly during the first 6 months or so of life, then usually shrink and disappear by the time a child is 5 to 10 years old. Some, particularly larger ones, may leave abnormal skin as this happens. Surgery can fix this. Others may leave red pigmented skin, which can be helped with special laser treatment. Although they can be anywhere on the body, most hemangiomas are on the head or neck. They can cause problems if they interfere with sight, feeding, breathing, or other body functions.

 These discolorations look like wine was spilled on an area of the body, most often on the face, neck, arms, or legs. Port-wine stains can be any size, but grow only as the child grows. They tend to darken over time, and can thicken and feel like pebbles in middle adulthood unless treated. They never go away on their own. Doctors will watch ones near the eye to make sure they don’t cause problems. When port-wine stains involve certain parts of the face, other tests (such as an MRI) might be needed.

Pigmented Birthmarks

The most common pigmented birthmarks are café-au-lait spots, Mongolian spots, and moles: