Fetal alcohol syndrome (FAS) and Down syndrome are both conditions that are present at birth. While they both affect facial appearance, development, and physical health, they have different causes.

Exposure to alcohol during fetal development can cause fetal alcohol spectrum disorders (FASDs), of which FAS is one type. In contrast, Down syndrome occurs in people who have an extra copy of chromosome 21. This is why doctors also call it trisomy 21.

Read on to learn more about fetal alcohol syndrome versus Down syndrome.

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FAS has some similarities to Down syndrome in terms of symptoms, but the causes are distinct. Either condition may cause:

  • developmental delays
  • physical differences or health conditions
  • distinctive facial features
  • learning disabilities

However, it is important to note that both FAS and Down syndrome exist on a broad and varied spectrum. Two people with the same diagnosis can have very different symptoms and need different types of support.

Additionally, while both conditions usually involve a degree of intellectual disability, it can sometimes be minor.

Down syndrome usually affects appearance, but the developmental delays it can cause can sometimes be mild. Some people with Down syndrome or FAS do not have any major health conditions at birth.

While FAS and Down syndrome can affect people in similar areas, there are differences in the symptoms. Not all people with FAS or Down syndrome will have all the symptoms.

Because the signs can vary and there is some overlap, only a doctor can provide a firm diagnosis.


Most people with Down syndrome have differences in appearance. In comparison to people without Down syndrome, those with the condition tend to have:

  • smaller heads
  • flatter faces and noses
  • hooded or slanted almond-shaped eyes
  • tiny white spots on the iris of the eyes
  • small ears
  • a short neck
  • a shorter-than-average height
  • a single line across the palms of the hands
  • low muscle tone

People who have a rare type of Down syndrome known as mosaic Down syndrome may not have as many noticeable facial signs.

FAS can also cause a shorter height, but the facial features are different from those of Down syndrome. They may include:

  • a thin upper lip
  • a smooth ridge between the nose and the upper lip
  • shorter, narrower eyes

Physical health

Some health conditions are common among children with Down syndrome, including:

  • infections
  • hearing loss
  • vision problems
  • obstructive sleep apnea
  • endocrine disorders, especially an underactive thyroid
  • heart defects
  • epilepsy
  • gum or teeth problems
  • digestive conditions, such as celiac disease
  • blood disorders, including an increased risk of leukemia

In comparison, FAS always comes with physical health conditions or challenges. This is what separates FAS from other FASDs, some of which affect only a person’s cognitive abilities and behavior.

FAS causes growth delay, which may include a low birth weight and slow growth after birth. It may also result in:

  • difficulty with coordination
  • difficulties sleeping or sucking as a baby
  • difficulties with vision or hearing
  • conditions that affect the heart, kidneys, or bones

Learning ability

Both Down syndrome and FAS can cause:

  • delays in hitting developmental milestones
  • delayed or slow speech
  • lower-than-average IQ
  • difficulty paying attention
  • difficulty remembering things
  • difficulty with reasoning and judgment

However, abilities vary significantly in people with Down syndrome or FAS.

Mental health

Both FAS and Down syndrome can affect a child’s ability to manage their emotions. They may have strong feelings that they express as anxiety, anger, or in some cases, aggression.

As a secondary effect, the experience of living with FAS or Down syndrome may contribute to mental health difficulties such as depression. Challenges in socializing with others and living independently or experiences of ableism may have a negative impact.

Like other children, those with FAS or Down syndrome can have other diagnoses at the same time, such as autism or attention deficit hyperactivity disorder (ADHD). Children with Down syndrome are not more likely to have these diagnoses than children without Down syndrome but may have more difficulty coping with their effects.

There is no evidence that drinking alcohol in pregnancy causes Down syndrome.

Down syndrome is a chromosomal condition. Chromosomes are the packages for DNA, which tells cells how to divide and grow.

Humans have 23 pairs of chromosomes. Down syndrome occurs when a person has an extra copy of chromosome 21, meaning they have three copies.

Researchers do not fully understand why some people have the extra chromosome. While it can occur in anyone, it is more common in babies born to older parents, often those over the age of 35 or 40 years.

A baby with Down syndrome who had exposure to alcohol before birth could potentially have FAS, too, but the two conditions are not the same.

To diagnose FAS or Down syndrome, a doctor may first ask questions about the child’s symptoms, perform a physical examination, and take a medical history.

If they suspect Down syndrome, they can request genetic testing for an extra chromosome to confirm it. Amniocentesis or other tests may reveal a Down syndrome diagnosis before birth.

No single test can diagnose FAS, but doctors may diagnose the condition based on a child’s appearance, the presence of developmental delays, and known alcohol exposure during pregnancy. A complete medical history is important for the diagnosis.

Doctors may also recommend other tests to rule out other causes, such as screening for mental health conditions, autism, or other neurological conditions.

While both FAS and Down syndrome are lifelong conditions, there are many interventions that can help children learn skills, reach developmental milestones, and manage physical conditions.

The exact interventions that will help will depend on the child’s needs, and support may come from a team of health professionals.

The treatment plan may include:

  • surgery to address physical conditions such as heart defects
  • early interventions, such as speech therapy and physical therapy, to improve skills in childhood
  • caregiver education and training
  • occupational therapy, which teaches people how to adapt everyday tasks to their needs
  • educational support, which may include:
    • placement in a special education school or classroom
    • an individualized education program
    • accommodations that make school more accessible
    • additional tutoring
  • emotional or behavioral therapy, which can help children learn how to manage emotions and communicate with others more effectively and can encourage helpful behaviors
  • medications to help with attention difficulties, hyperactivity, depression, or other conditions
  • support groups
  • future planning, including financial and legal support to ensure that a child has the care they need in adulthood

The outlook for FAS or Down syndrome depends largely on how the condition affects a person, their home environment, and their access to early intervention.

Outlook for Down syndrome

Down syndrome can range from mild to severe, so the outlook for health, quality of life, and life expectancy varies.

Increasingly, children with Down syndrome are able to complete education, pursue higher education, learn to drive, begin careers, and live independently.

But there can still be challenges, particularly when children with Down syndrome transition to adulthood and when they experience the typical hormonal fluctuations of adolescence.

People with Down syndrome also have a very high risk of mid- and late-life neurological disorders, and 50–70% may develop Alzheimer’s disease by the age of 60 years.

Outlook for FAS

FAS is the most involved diagnosis on the FASD spectrum. It affects both cognition and physical growth and development. In a 2023 study in Germany, researchers found that symptoms affecting brain function in people with FASDs were often complex.

A stable, positive, and nonviolent home environment is one of the most important factors for helping children with FASDs. However, a lack of awareness, stigma around the condition, late diagnosis, and difficulty accessing care can all create barriers.

This is why it is important for a person to speak with a doctor as soon as possible if they think that their child might have FAS or another developmental disorder.

FAS and Down syndrome have some similar symptoms, but they are distinct diagnoses with different causes.

There is no specific treatment for either condition, and the course of either condition varies from person to person. As a result, healthcare professionals tailor support and medical interventions to each child.

Children with FAS or Down syndrome may need comprehensive support and may continue to need it throughout their lives. A person should speak with a doctor if they notice signs that a child may have one of these conditions.