Why and is it a bad thing that my birthmark changes colors?

Question

Why and is it a bad thing that my birthmark changes colors?

Answer 1

 please dont believe what guest8367 said, its not true. I have a birthmark too that hasnt got texture or anything just a long red/pink mark all over my right arm and a little bit over my back. When I am cold for example, my birthmark changes to a darker colour like purple/red but its just because of the flow of blood, the same that happens when you are cold and your lips get darker, its normal so dont panic ;)