Birthmarks are one of those little mysteries that many babies are born with. Some are tiny and faint, while others are more noticeable and change over time. In this episode, we explore why birthmarks happen, the different types you might see, and what they can tell you about how your baby’s skin develops. From pigmented spots to vascular marks like hemangiomas and port-wine stains, you’ll learn what causes them, why some fade and others don’t, and when it’s worth mentioning them to your pediatrician.

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Hi Vanessa,

Thank you for everything you do with the Pregnancy Podcast. I listened to your episodes throughout my entire pregnancy, and they were such a huge help. I felt so much more informed and confident going into birth because of the information you shared. My doctor was even impressed by how much I knew.

My son was born a few weeks ago, and we’re both doing great. He has a few small birthmarks, and it got me curious about what causes these. I’ve read a little online, but the explanations seem all over the place. I’d love to understand more about why birthmarks happen, and if they will go away with time. If this is something you might cover in a future episode, I think a lot of parents would appreciate it.

Thank you again for all the information you share and for helping me feel so supported during my pregnancy.

Warmly,

Hannah

Hannah, thank you for your kind words about the podcast, and I am so glad it was helpful for you during your pregnancy. Congrats on your baby boy. It is great to hear you are both doing well, and I hope you are enjoying the first weeks of motherhood.

What is a birthmark?

A birthmark is an area of skin that looks different from the surrounding skin and appears at birth or shortly afterward. These marks are very common and, although they can be concerning for new parents, they are almost always harmless.

Birthmarks form because of slight differences in how skin cells develop or function. Some are visible at birth, while others appear in the first few weeks or months of life. This happens as a baby’s skin matures and produces more pigment, revealing variations in color or texture. Melanocytes play a key role in this process. These are the cells that produce melanin, which is the pigment responsible for the color of your skin, hair, and eyes. As pigment production increases, the differences between normal and abnormal skin pigmentation become more noticeable, making some birthmarks easier to see over time.

What Causes Birthmarks?

Birthmarks occur when certain cells grow or behave differently from the surrounding skin cells during development. These differences can involve melanocytes, the pigment-producing cells that create melanin, leading to areas of darker or uneven color. They can also involve blood vessels that grow more densely in one spot, forming vascular birthmarks. In some cases, birthmarks affect other parts of the skin’s structure, such as connective tissue or lymphatic vessels, causing slight changes in texture or small, fluid-filled areas under the skin.

It is important for parents to know that they cannot cause or prevent birthmarks by doing or not doing anything during pregnancy. These differences occur naturally as a baby’s skin and blood vessels develop and are completely beyond your control. It is normal for parents to worry about how a birthmark looks or whether it will change. Let’s examine the different types of birthmarks so you have a better understanding of them.

Types of Birthmarks

There are two main categories of birthmarks: pigmented and vascular.

Pigmented Birthmarks

Pigmented birthmarks occur when pigment-producing cells (melanocytes) grow or cluster together in one area. They can range in color from tan to brown, gray, black, or even blue. The three main types of pigmented birthmarks are café-au-lait spots, moles, and Mongolian spots.

Café-au-lait Spots

“Café-au-lait” means “coffee with milk” in French, describing their light brown color. These flat patches form when there is an increased amount of melanin in the skin. They are harmless and very common in children of all skin tones.

Moles

Moles form from clusters of melanocytes that develop before birth. When present at birth, they are called congenital nevi. It is normal for moles to darken or grow as your child grows.

Mongolian Spots

The last type of pigmented birthmarks are Mongolian spots. The term “Mongolian spot” was coined in the late 1800s by a physician who observed them in babies of Mongolian descent. These types of birthmarks occur in babies of many ethnic backgrounds, and many doctors today prefer the term dermal melanocytosis. These are caused by melanocytes that get trapped or remain deeper in the skin rather than moving to the surface during development. Because the pigment is deeper, the spot appears blue, gray, or even greenish rather than brown.

Vascular Birthmarks

Vascular birthmarks occur when blood vessels form differently or cluster together in one area. These are quite common. One study estimated that they affect about 1 in 10 babies. Another found a prevalence of 20–30%. There are three main types of vascular birthmarks: salmon patches, hemangiomas, and port-wine stains.

Salmon Patches

Also called nevus simplex, salmon patches are flat, pink or red marks caused by dilated capillaries near the skin’s surface. Salmon patches on the forehead, eyelids, nose, or upper lip, are affectionately referred to as angel kisses. When they appear on the back of the neck, they are known as stork bites. These marks result from small clusters of blood vessels that developed differently during early growth in the womb. The process is random, and there is no predictable pattern or reason a birth mark appears in one area over another.

Hemangiomas

Hemangiomas are benign overgrowths of blood vessels that form in one area. Some people call these strawberry marks because of their bright red color and raised, bumpy appearance. Hemangiomas can be superficial, appearing on the surface of the skin and bright red. They can also be deep, developing below the surface, and appear bluish or purple. It is also possible for a hemangioma to be a combination of both. Hemangiomas typically go through three phases. In the growth phase, they grow quickly during the first 6–9 months of life. In the rest phase, growth stops and the mark stabilizes. Then in the involution phase the mark will gradually shrink and fade. Research shows that about 50% disappear by age 5, 70% by age 7, and 95% by ages 10–12.

Port-Wine Stains

Lastly are port-wine stains. These are caused by dilated capillaries that do not constrict properly. Unlike other vascular birthmarks, these do not fade and may darken or thicken over time. They can appear anywhere on the body but are most commonly on the face and neck. Port-wine stains are less common than other types, affecting about 0.3% to 0.5% of newborns.

Talking to Your Pediatrician

Most birthmarks are completely harmless and simply part of what makes your baby unique. Still, it is always a good idea to mention any birthmarks to your pediatrician. They can identify what type of birthmark it is, explain what to expect over time, and let you know if it needs any monitoring.

In rare cases, certain types of birthmarks can be a sign of underlying conditions that affect blood vessels, nerves, or other tissues. As an example, a large port-wine stain near the eye may warrant an eye exam to check for related changes, or multiple café-au-lait spots could prompt a closer look for a genetic condition. Most of the time, these evaluations are precautionary and help ensure that your pediatrician does not miss anything important. Your pediatrician may simply take a photo and track any changes in size, shape, or color at regular visits. If needed, they can refer you to a pediatric dermatologist or another specialist for a closer look.

In the vast majority of cases, your pediatrician will reassure you that the mark is benign and may fade or stay the same without causing any problems. If a birthmark is especially large or prominent, your pediatrician may discuss treatment options. Some marks can be lightened with laser therapy, and certain hemangiomas may respond to medication that helps shrink the blood vessels.

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Save 10% on 8 Sheep Organics

The True Belly Serum from 8 Sheep Organics is specially formulated with clinically proven ingredients that penetrate deep into the skin to effectively prevent stretch marks. Like all 8 Sheep products, the True Belly Serum comes with a 100-day Happiness Guarantee. You can try it completely risk-free for 100 days! Click here to save 10%.