Fetal Alcohol Syndrome, or FAS (F-A-S), is the name given to a group of physical and mental birth defects that are caused by drinking alcohol during pregnancy. It's generally believed to be the result of heavy drinking, although there's no conclusive evidence about the amount of alcohol necessary to cause defects in an unborn child. The three main characteristics used to diagnose FAS are low birth weight, facial abnormalities, and damage to the central nervous system, which may result in mental retardation, coordination problems, and learning disabilities. Once the damage is done, it cannot be undone, but FAS is the only cause of birth defects that can be completely prevented. Since there's some uncertainty about how alcohol affects unborn children, the only sure way of avoiding complications due to alcohol is by not drinking during pregnancy. However, if you choose to drink small quantities of alcohol, it's a good idea to discuss the possible ramifications with your doctor. In addition, if you're an alcoholic or a problem drinker, you should inform your doctor, and consider enrolling in treatment program. For more information about Fetal Alcohol Syndrome, consult a health care professional in your area.