When it comes to the cause of birthmarks, there are many factors that can affect this skin condition. One in ten children will have a colored mark on his or her skin at birth. Sometimes this mark is smooth and other times it will be raised and red in appearance. These birthmarks can be hidden behind hair or can be a splotch of red stretched across a child's forehead or stomach. The following are some things that affect and cause birthmarks.

There are some birthmarks that are the result of abnormal pigmentation and blood vessel growth while the fetus is developing. For example, if you have a strawberry birthmark, it is often the result of an overgrowth of fine blood vessels. This gives the mark its texture and red color. Such an overgrowth can happen both on the surface of the skin and on internal organs. If the growths are harmful to one's basic activities, like blinking, or are particularly unsightly, skin treatments or removal options like laser therapy and surgery can remove such abnormalities.

Birthmarks can be the cause of genetics and can be hereditary. For example, if a child's parents or grandparents or some other family member had Mongolian spots when they were born, it is then more likely that the child will also experience this. Though birthmarks can be hereditary, they are not the cause of something the mother did during pregnancy. Strawberry birthmarks do not occur because a woman had too much or too little of red-colored fruits and are not the result of a major scare.

For brown-colored birthmarks like café au lait spots, the cause may be an overgrowth of pigment cells. These cells, called melanocytes, may form abnormally, and thus, the child may be born with something as small as a few dots to patches of dark-colored skin. Really, the amount of melanin and the location of this substance often determine the darkness or color of such birthmarks.