Fetal alcohol syndrome is a confusion of permanent birth defects that happens in the offspring of women who drink alcohol during pregnancy. It is unidentified whether amount, frequency or timing of alcohol using up during pregnancy causes a difference in degree of harm done to the fetus. Thus, the current recommendation is not to drink at all in pregnancy. Alcohol crosses the placental barrier and can feat fetal growth or weight, create characteristic facial stigmata, damage neurons and brain structures, and cause other physical, mental, or behavioral problems.

The major effect of Fetal alcohol syndrome is lasting central nervous system damage, especially to the brain. Developing brain cells and structures are immature or malformed by prenatal alcohol exposure, often creating an array of primary cognitive and functional disabilities as well as secondary disabilities. The hazard of brain damage exists in each trimester, since the fetal brain develops throughout the entire pregnancy.