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Mongolian spots, stork bites and more: all about birthmarks

Do you know your strawberry marks from your stork bites? Your cafe-au-lait from your Mongolian spots? We’ll help you sort out which birthmark is which.

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Mongolian spots, stork bites and more: all about birthmarks

What are birthmarks?

Birthmarks are coloured blemishes on the skin that are noticeable at birth, or shortly afterwards [1]. They’re certainly not rare – many children will have a birthmark of some sort, although it’s not known why some children have birthmarks and others don’t [2].

There are many different kinds of birthmarks. They can be any size or shape and can be different colours, such as blue or blue-grey, brown, tan, black, pink, white, red or purple. Some birthmarks are smooth and some are raised or lumpy. But what most of them have in common is that nearly all are harmless and painless [3]. However, there are a few that can require treatment based on where they are located and whether they’re growing in size or changing colour[4].

Many birthmarks go away on their own by the time a child is of school age, but some may remain on the skin permanently. There is also no way to prevent birthmarks from occurring[5].

What causes birthmarks?

In general, birthmarks happen by chance and certainly aren’t caused by anything the mother did or didn’t do during her pregnancy, though some myths and old wives’ tales suggest otherwise[6].

Dermatologists divide birthmarks into two main categories: vascular birthmarks and pigmented birthmarks[7].

Vascular birthmarks are marks made up of excess or abnormal blood vessels under the skin[8]. There are many different types and they’re often red, pink or purple in colour[9].

In 1997, a study was published in the Journal of Hepatology that claimed to have found that some vascular birthmarks displayed inheritance patterns in families. Researchers found the majority of inherited vascular malformations (in particular) occur with equal frequency in males and females and carry a 50 percent risk of children inheriting them. Although they also acknowledge that environmental factors play a role in their development as well [10].

Since then, a groundbreaking study published in the New England Journal of Medicine in 2013 offered conclusive scientific evidence that points to an in-utero genetic mutation as the direct cause of port-wine-stain marks and Sturge Weber Syndrome [11].

Pigmented birthmarks, on the other hand, are possibly caused by clusters of excess skin pigment cells and are tan or brown coloured skin marks[12]. These birthmarks can be flat or elevated and may simply be due to excessive deposition of melanin pigment in the deeper layers of the skin called dermal melanosis [13].

While the exact cause of pigmented birthmarks is still unknown, the amount and location of melanin in the skin determines the actual colour of pigmented birthmarks[14].

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