Congenital nevi is a term used to describe a group of birthmarks that appear on the skin of an infant. It is not known what causes birthmarks, and there is no way to prevent them from forming in the womb. Different types of nevi can range in size from a pinpoint to a mark that covers half of the body. Moles, strawberry birthmarks, stork bites, port wine stains, and Mongolian spots are all types of nevi.
Birthmarks can be light tan, purple, blue, dark brown, red, pink, or deep red to black in color. They can be raised or flat, and irregular or uniform in shape. If a large number of nevi or one single large nevus is present, the child needs to be evaluated by a physician.
Congenital nevi are not harmful to a child and usually do not require intervention by a physician. Prominent nevi or those located on the face may cause social problems for the child or result in an altered sense of body image. Support groups and counseling may ensure the emotional well-being of the child.