Fetal alcohol syndrome (FAS) is a collection of birth defects that occur when a fetus is exposed to alcohol. These range from learning and behavioral difficulties to mental retardation. Death of the fetus is the most extreme outcome. 

A woman who drinks at any point during pregnancy puts the fetus at risk of FAS. Generally, the more alcohol consumed during pregnancy, the greater the risk of FAS and the more severe the symptoms. However, exactly how much alcohol causes defects is not known, and appears to vary from person to person and from pregnancy to pregnancy. 

About 1,200 children are born with FAS every year, according to the American Academy of Family Physicians. The U.S. Department of Health and Human Services estimates that 40,000 are born with some signs of prenatal exposure to alcohol.

FAS is not diagnosed until after a child is born. A medical history may include questions about a mother’s alcohol intake during pregnancy. A physical examination may be conducted to determine the extent of deficiencies, as well as to rule out other potential causes of a child’s symptoms.

Children with FAS will have certain distinctive facial abnormalities, physical growth deficiency (e.g., height and/or weight) as well as central nervous system problems. Children who exhibit some but not all signs required for a diagnosis of FAS may have another type of fetal alcohol spectrum disorder (FASD). FASD is a term used to describe the range of detrimental effects that can occur in an individual whose mother drank alcohol during the pregnancy. It is not intended for use as a clinical diagnosis. 

There is no cure for FAS. Most treatment focuses on addressing the special education or medical needs of children with FAS. However, the physical, mental or behavioral defects in children with FAS are lifelong, irreversible problems. Parents of children with FAS can seek out emotional or respite services that may be available in their communities. They may also help their child by providing a nurturing and supportive home environment.

FAS is completely preventable. Women who are pregnant (or may become pregnant) should eliminate all alcohol consumption for the duration of pregnancy. Abstinence is the only proven method to prevent birth defects as the result of fetal alcohol exposure. Prior to 1973, when FAS was recognized by the scientific community in the United States, women may have been advised that low levels of alcohol during pregnancy were safe. However, it is now understood that no amount of alcohol is safe during pregnancy.