What are Birth Marks caused from?

A birthmark (also known as nevus) is a result of a development abnormality of the skin. One possible cause is that during the embryonic stage of fetal development (first trimester), cells that belong in the mesoderm (blood forming middle germ layer) get displaced in the ectoderm (skin forming outermost cell layer). This leads to proliferation of blood vessels or abnormal pigmentation in the dermal and epidermal structures of the skin, resulting in birthmarks. Birthmarks are perceived to be non-hereditary. In addition, twice as many females as males are observed to have various forms of birthmarks. However, scientists have not yet come up with an explanation for these phenomena.----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Birthmarks fall in to two main categories, vascular birthmarks, and pigmented birthmarks. Vascular birthmarks (also known as hemangioma) are made of the abnormal proliferation of tiny blood vessels (capillaries) and related to vascular skin changes. They are rarely fully-grown at birth.Hemangiomas observed to be more common among females than males, with 5 times as much females having hemangioma. Another interesting observation is that hemangiomas occur predominately in Caucasian people as opposed to dark skinned people. It has also been noted that low birth weight infants of less than 2.2 pounds have a 26% chance of being born with or developing a hemangioma shortly after.

This is my personal believe.....When your in mother ...say your hand is sitting on you leg for a long period of time while growing inside her.....thats what leaves a birthmark....understand???....

The cause of most birthmarks is unknown. Most birthmarks are not inherited. Most vascular birthmarks are not due to difficulties or problems that happen to the mother during pregnancy.