Birthmarks form when there is an excess of pigment cells or blood vessels bunched up in one area of the skin. No one really knows why this happens. Some types of vascular birthmarks may run in families, but often that’s not the case. Birthmarks have never been linked to diet, lifestyle or anything a mom may or may not have done, or been exposed to, before or during pregnancy or childbirth. Birthmarks just happen.
Next: Types of Birthmarks
