One to 10 percent of babies are born with a birthmark. Most are harmless and fade over time. Birthmarks come in all shapes and sizes. Some are hard to find, others are impossible to miss. Some are visible at birth, others appear weeks or months later. They can be flat or raised, and any of a wide range of colors. But no matter how large or small, seeing a birthmark on your newborn can be scary for any parent. Was it something I did? Or didn’t do?

Vascular birthmarks appear when a several blood vessels get twisted together. The most common vascular birthmarks are macular stains (also called angel kisses or stork bites), port wine stains, and hemangiomas (often called strawberry hemangiomas). A  hemangioma usually gets larger during the first year, forming a red, spongy mass that protrudes from the skin, but then gets smaller over time. Ninety percent of hemangiomas disappear by 10 years of age, so treatment is rarely needed.

Pigmented birthmarks are caused by an overgrowth of the cells that produce pigment in skin. The most common pigmented birthmarks are cafe-au-lait spots, Mongolian spots, and moles. Pigmented birthmarks can be found anywhere on the body and can increase in number as a child gets older. Mongolian spots are flat, bluish-gray patches on the lower back or buttocks. They are usually found on darker skinned children, such as on children of Asian, American Indian, African, Hispanic, and Southern European descent. Mongolian spots usually fade by the time a child is 5 years old. Most people get moles (nevi) at some point in life. A mole present at birth is called a congenital nevus and will last a lifetime. Large congenital nevi are more likely to become cancerous (melanoma) later in life. Smaller moles have only a slight increase for cancer. Moles can be tan, brown, or black; flat or raised; and may even have hair growing out of them (hairy nevi). Pigmented birthmarks are best left alone, with the exception of moles, which are often surgically removed. Some birthmarks, such as port wine stains, respond well to laser therapy.

No one knows for sure what causes birthmarks. It’s important for parents to know that it wasn’t caused by something they did (or did not do) during pregnancy. Seeing a birthmark on your newborn can be alarming because it’s unexpected. Birthmarks seldom pose a health risk but can damage a child’s self-esteem as they get older, especially if the birthmark is obvious. Talking openly about a birthmark helps kids accept it as simply another part of who they are—green eyes, curly hair, brown mole on cheek. You can help your child manage the stares and questions by arming them with a simple response, i.e., “It’s just a birthmark. It’s been there since I was born.” Children with a permanent birthmark that is disfiguring will need additional emotional support from family and friends. But they also need to know that they are normal in every other way.