A port wine stain is a red or purple mark that is usually present from or immediately after birth, often affecting the face, although they can form elsewhere on the body.
It is thought that approximately three babies out of every one thousand are affected by port wine stains of varying sizes, shapes and colours.
These birthmarks develop when blood vessels beneath the skin remain dilated all the time, hence the dark red or purple colour of the blood immediately beneath the surface of the skin. One possible cause could be damaged nerves that serve the blood vessels and fail to transmit the nerve impulses that cause blood vessels to contract.
Port wine stains tend to darken with age, which means it is generally a good idea to seek treatment earlier rather than later. While smaller birthmarks can be effectively camouflaged using specialist make up, laser port wine stain removal is generally the preferred course of treatment.
Even small children can undergo this type of treatment, indeed there is a higher success rate in smaller children with more recently-developed marks. Another benefit to earlier treatment is that any emotional impact of having the birthmark will be minimised.