Fetal alcohol syndrome (FAS) is the term for severe birth defects caused by heavy alcohol use (5 or more drinks on at least one occasion) during pregnancy.

Children with FAS have:

• Characteristic facial features, which include a small head, flat face, narrow eye openings (slits), a short upturned nose, a flattened groove between the nose and the upper lip (philtrum), and a thin upper lip. Although a single trait may be hard to pick out, the head and face just don't seem to "look right" in a child with FAS.
• Low birth weight and slowed growth. A newborn weighs less than 2500 g (5.5 lb) As children with FAS grow, they are at or below the 10th percentile in height or weight (or both) in growth charts that compare them with other children of the same age and sex.
• Central nervous system abnormalities, including small head size, mental retardation, poor fine motor skills, or poor eye-hand coordination.
• Behavior and thinking (cognitive) problems, which may include poor attention, concentration, memory, and comprehension skills; difficulty with math skills; hyperactivity; and extreme mood changes.

A child with FAS may also have birth defects that involve the eyes, ears, heart, urinary tract, or bones.