answersLogoWhite

0

Birthmarks - marks present on the skin at birth - may be caused by:

1.) minor malformations of blood vessels;

2.) high concentrations of melanocytes in an area of skin;

4.) trauma whilst passing down the birth canal when being born.

Some are permanent; others are not, & fade/ disappear in early life.

"Classic" brown or black birthmarks may be due to genetic anomalies: some seem to be hereditary, appearing on the same areas of the bodies of different members of the same family; others occur randomly on individuals. "Mongolian marks" (usually bluish/ grey colour) occur frequently on babies of Asian ancestry. Brown birthmarks tend to occur on white people (5-10% frequency in most populations), although black people may have them too: they're most frequently located on the trunk, buttocks & legs; they occur more in women than men, & are most common on blondes/ fair skinned people, and especially redheads. Exactly why this is is uncertain, but it's most probably a genetic cause.

Such naevi are caused by an unusually high concentration of melanocytes in one area of skin; they may be regular or irregular in shape; large (ie >1.5 cm across) or small (commonly called "moles"); flat or raised; some may be hairy. Generally, such marks are harmless (cosmetic considerations aside), although multiple "cafe au lait" marks on one person may indicate certain neurological conditions.

The "Becker's Naevus" is a male "birthmark" - typically fairly large/ hairy, occurring on chest/ upper back - that emerges on some men (approx 0.2%) at or after puberty: seemingly stimulated by testosterone. Technically, because not present at birth, these are not birthmarks, but because they're almost certainly genetically determined (in a sense congenitally "programmed" to appear later) most regard them as such.

Other birthmarks are vascular - "port wine" marks are usually caused by abnormal dilation of blood vessels near the skin surface. If extensive, & on the head/ face, they may be associated with blood vessel abnormalities inside the head as well. Generally, however, such marks are harmless.

Many birthmarks are nothing more than the result of the traumas/ pressures experienced by the baby during birth: bruises/ contusions, minor extrusions of blood vessels etc (eg many so called "Strawberry marks"), and, in most cases, they fade and usually disappear in early life.

So, you "get" a birthmark either because of some minor developmental glitch whilst in the womb, or because of the traumas of birth itself.

User Avatar

Wiki User

14y ago

What else can I help you with?