Fetal alcohol syndrome (FAS) and fetal alcohol effects (FAE) are conditions associated with drinking alcohol during pregnancy. FAS causes a variety of mental, physical, and developmental disabilities in the baby. FAE is a milder form of FAS.
If a pregnant woman drinks any alcohol at any time during pregnancy, the alcohol crosses the placenta to the fetus. Alcohol damages the developing cells of the fetus. The brain and central nervous system are particularly sensitive to alcohol and can suffer permanent damage.
Any amount can have some effect, so there is no minimum amount of alcohol in pregnancy that is safe. The developing fetus can't break down the alcohol as quickly as an adult, so its exposure to alcohol is actually higher than the mother's.