not fade with age. Such birthmarks may have emotional or social repercussions. Port-wine stains occur in 0.3% of the population, equally among males and females. They frequently express unilaterally, i.e., on only one side, not crossing the midline of the body. Often on the face, marks on the upper eyelid or forehead may be indicative of a condition called Sturge–Weber syndrome. Additionally, port-wine stains in these locations may be associated with glaucoma and seizures. Treatment Most birthmarks are harmless and do not require treatment. Pigmented marks can resolve on their own over time in some cases. Vascular birthmarks may require reduction or removal for cosmetic reasons. Treatments include administering oral or injected steroids, dermatological lasers to reduce size and/or color, or dermatologic surgery. Historical explanations Many explanations were given to explain the origin of birthmarks. Occasionally, it was said that children could be 'marked' or 'imprinted' upon by scares or frights given to the mother during the pregnancy, which draws on the outdated theory of maternal impression. Children are also said to be marked by some sudden fright or unpleasant experience of the mother, and I have myself seen a pop-eyed, big-mouthed idiot whose condition is ascribed to the fact that his mother stepped on a toad several months before his birth. In another case, a large red mark on a baby’s cheek was caused by the mother seeing a man shot down at her side, when the discharge of the gun threw some of the blood and brains into her face.Other explanations claimed that birthmarks shaped like food were the direct result of the mother's pregnancy cravings, or the mother touching a certain part of her body during a solar eclipse - her child's birthmark will be in the same location. References External links Birthmarks via the Cleveland Clinic Vascular Birthmarks Foundation Birthmarks via MedlinePlus Skin