What is Fetal Alcohol Syndrome?

Fetal alcohol syndrome (FAS) refers to a set of physical and mental defects that are caused by a mother consuming alcohol during pregnancy. The severity of FAS symptoms varies from child to child, but all defects that do occur are irreversible.

Fetal Alcohol Syndrome, Causes, Signs and Symptoms, Diagnosis and Treatment.

Alcohol consumption during pregnancy

No amount of alcohol has been shown to be safe to consume during pregnancy and anyone who drinks during this time places their baby at risk of developing FAS. A woman’s child is at risk of FAS at any point during her pregnancy, as development is ongoing throughout the entirety of the gestational period.

Worldwide, FAS is one of the most common causes of impaired intellectual ability, and in the United States, the condition is thought to cause intellectual disability in up to 2 in every 1,000 babies born. It is estimated that in the United Kingdom, between 6,000 and 7,000 babies are born with FAS each year.

Experts believe that this rise in FAS cases represents an improvement in the ability to diagnose this condition, but it also reflects the ongoing failure to address and solve alcohol abuse.


FAS is caused by alcohol in the mother’s bloodstream crossing the placenta and reaching the fetus. The blood alcohol concentration in the developing fetus is much higher than in the mother’s blood because the fetus metabolizes alcohol much more slowly than the mother does.

In the fetus, alcohol impairs the delivery of oxygen and nutrients to developing tissues and organs. The brain, heart, bones, and central nervous system (CNS) may all be affected if a mother drinks during the first trimester, which is when these specific parts of the fetus are undergoing key stages in development. Damage to the baby may also be caused by drinking at any other point throughout the pregnancy.


The signs and symptoms of FAS vary widely and include a mixture of physical, cognitive, and behavioral difficulties that affect the child’s ability to function on a daily basis and cope with everyday life.

Physical defects

Some of the physical defects typically seen in children with FAS include:

  • Distinctive facial features include wide-set eyes, the absence of the groove between the nose and upper lip (the philtrum), a thin upper lip, and an upturned nose.
  • The limbs, joints, and fingers may be deformed
  • Delayed growth during and after birth
  • Hearing and visual disturbances
  • Heart, kidney, and bone defects
  • Small head and brain size (microcephaly)

CNS defects

One of the main effects of FAS is damage to the CNS, particularly the brain. The development of certain parts of the brain may have been disrupted by exposure to alcohol, which can lead to various problems such as:

  • Poor memory
  • Attention deficit disorder (ADD)
  • Intellectual disabilities
  • Learning disabilities
  • Difficulty processing information
  • Hyperactivity
  • Poor cognitive skills, such as reasoning or problem solving
  • Poor judgment skills and difficulty evaluating consequences of choices
  • Rapidly changing emotional state

Effects on behavior

The effects FAS has on physical features and the CNS can lead to behavioral issues, as children find it difficult to cope and interact with others. Some of the problems these children typically face include:

  • Poor social skills and difficulty getting along with other children
  • Difficulty in school
  • Difficulty switching between tasks and dealing with change
  • Impulsivity and poorly controlled behavior
  • Difficulty planning and achieving a goal


FAS can be difficult to diagnose because there is no blood test for the condition and the symptoms often overlap with those of other conditions such as attention deficit hyperactivity disorder (ADHD) and Williams Syndrome. However, when diagnosing this syndrome, doctors will usually look for the following signs and symptoms:

  • Abnormal facial features (see above)
  • Below average weight and/or height
  • CNS disorders (see above)
  • History of maternal intake of alcohol during pregnancy


There is no cure for FAS and the defects that these children are born with affect them for their entire lives. However, early intervention services are available to help children with the condition and try to prevent some of the problems that can develop in the future. These interventions typically include:

  • Speech and hearing therapy
  • Physical therapy to aid walking, for example
  • Services in schools for children experiencing learning or behavioral issues
  • Counseling for parents and other family members to help them cope with associated problems, such as behavioral issues
  • Medication to relieve certain symptoms
  • Medical intervention to address health problems, such as a heart defect
  • Treatment for alcoholism to help the mother improve her parenting and prevent the likelihood of any further pregnancies being affected by the condition


Further Reading

Last Updated: Feb 16, 2023

Sally Robertson

Written by

Sally Robertson

Sally first developed an interest in medical communications when she took on the role of Journal Development Editor for BioMed Central (BMC), after having graduated with a degree in biomedical science from Greenwich University.


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