Birthmarks are patches of skin that look different from the skin around them. They are formed before birth or shortly after, and they are caused by variations in how skin cells, blood vessels, or pigments develop. Most birthmarks are harmless, but understanding why they appear can help you know when a mark requires a doctor’s attention.
What Causes a Birthmark to Form?
Birthmarks form during fetal development. They are not caused by anything the mother does during pregnancy. No food, stress, or action creates a birthmark.
The two main types of birthmarks are vascular and pigmented. Vascular birthmarks involve blood vessels that did not form correctly. Pigmented birthmarks involve an overgrowth of cells that produce color in the skin.
In vascular birthmarks, clusters of blood vessels develop in one spot. This creates a red or pink patch. In pigmented birthmarks, melanocytes — the cells that make skin pigment — multiply more than usual in one area. That creates a darker patch.
Genetics play a role in some types. For example, certain families have a higher rate of café-au-lait spots or other pigmented marks. But many birthmarks appear with no family history at all.
Are Birthmarks Genetic or Random?
Most birthmarks are random events during development. They are not inherited in a clear pattern. A parent with a birthmark does not necessarily pass one to a child.
Some genetic conditions include birthmarks as a symptom. Neurofibromatosis, for example, causes multiple café-au-lait spots. Sturge-Weber syndrome involves a specific port-wine stain on the face. These are rare conditions with known genetic links.
For the vast majority of people, a single birthmark is just a developmental quirk. It has no deeper meaning and no connection to future health problems.
How Are Vascular Birthmarks Made?
Vascular birthmarks form when blood vessels in the skin do not develop normally. Instead of a typical network of small vessels, the vessels cluster together or dilate in one area.
Salmon patches are the most common vascular birthmark. They appear as flat pink or red patches, often on the back of the neck, eyelids, or forehead. They are caused by dilated capillaries near the skin surface. Many fade on their own within the first year.
Hemangiomas are raised, red masses made of extra blood vessels. They often appear in the first weeks of life and grow rapidly for several months. Then they stop growing and slowly shrink. Most hemangiomas are gone by age 5 to 10, though some leave a slight mark or loose skin.
Port-wine stains are flat, dark red or purple patches caused by abnormally dilated capillaries. Unlike salmon patches, they do not fade. They persist through life and may darken or thicken over time.
Vascular birthmarks are not caused by injury during birth. They are present before delivery, even if they become more visible after the baby is born.
How Are Pigmented Birthmarks Made?
Pigmented birthmarks form when melanocytes cluster in one area of the skin. Melanocytes produce melanin, the pigment that gives skin its color. When these cells gather in higher numbers, the skin appears darker in that spot.
Café-au-lait spots are flat, light brown patches. They can appear anywhere on the body. A single spot is common and usually harmless. Multiple spots — six or more — can be a sign of a genetic condition, but this is uncommon.
Mongolian spots are flat, blue-gray patches usually found on the lower back or buttocks. They are common in babies with darker skin. They are caused by melanocytes that remain deeper in the skin during development. Most fade by school age.
Congenital nevi are moles present at birth. They range from small to very large. Large congenital nevi carry a slightly increased risk of skin cancer later in life, so they should be monitored by a dermatologist.
Pigmented birthmarks are not caused by sun exposure during pregnancy. They are formed by cell behavior during fetal development.
Can Birthmarks Be Prevented?
No. Birthmarks cannot be prevented. They form during development in the womb, and no action during pregnancy changes that process.
There is no evidence that diet, exercise, medication, or lifestyle choices influence whether a baby is born with a birthmark. Claims that certain foods or behaviors cause birthmarks are not supported by medical research.
If you are pregnant and worried about birthmarks, know that they are common. Many babies have at least one. They are not a sign of poor health or a problem with the pregnancy.
When Should a Birthmark Be Evaluated?
Most birthmarks require no treatment. But some need a doctor’s review.
See a doctor if a birthmark changes rapidly, bleeds, itches, or becomes painful. A mole that changes shape, color, or size after infancy should be evaluated.
Hemangiomas near the eye, nose, or mouth can interfere with vision, breathing, or feeding. These need early evaluation. Large congenital nevi should be checked by a dermatologist because of the small increased risk of melanoma.
Port-wine stains on the face near the eye can be associated with glaucoma or other eye problems. An eye exam may be recommended in these cases.
Most birthmarks are diagnosed by appearance alone. A doctor can usually tell the type just by looking. Imaging tests are rarely needed unless the birthmark is deep or near an organ.
What Treatments Exist for Birthmarks?
Treatment is not needed for most birthmarks. Many fade on their own. Others are simply a cosmetic difference that requires no intervention.
For those who want treatment, options exist depending on the type.
Laser therapy is the most common treatment for vascular birthmarks. It targets blood vessels and reduces redness. Port-wine stains respond well to multiple laser sessions. Salmon patches usually do not need treatment because they fade naturally.
Beta-blocker medications are used for hemangiomas that grow rapidly or interfere with function. Oral propranolol is the standard treatment for problematic infantile hemangiomas. It works by constricting blood vessels and slowing growth.
Surgical removal is an option for some pigmented birthmarks, particularly congenital nevi that are large or concerning. Surgery is not recommended for cosmetic reasons alone unless the mark causes significant distress.
No treatment is completely risk-free. Laser therapy can cause temporary redness or blistering. Surgery leaves a scar. The decision to treat should be made with a dermatologist or pediatric specialist, not based on marketing claims.
Do Birthmarks Fade With Age?
It depends on the type. Salmon patches and Mongolian spots often fade in early childhood. Hemangiomas shrink significantly but may leave a faint mark.
Port-wine stains do not fade. They persist through life and may darken or thicken with age. Café-au-lait spots usually stay the same. Congenital nevi can change over time and should be monitored.
There is no reliable way to predict exactly how a specific birthmark will evolve. A dermatologist can give a general expectation based on the type.
Frequently Asked Questions
Can birthmarks appear later in life?
True birthmarks are present at birth or appear within the first weeks of life. Marks that appear in adulthood are not birthmarks and should be evaluated by a doctor.
Are birthmarks caused by something the mother eats?
No. No food, drink, or activity during pregnancy causes birthmarks. They form during fetal development and are not linked to maternal behavior.
Do birthmarks need to be removed?
Most birthmarks do not need removal. Treatment is only considered when a birthmark interferes with function, carries a health risk, or causes significant distress.
Can a birthmark turn into cancer?
Most birthmarks never become cancerous. Large congenital nevi carry a slightly increased risk of melanoma, and any birthmark that changes in appearance should be checked by a dermatologist.
