Teratogens are environmental substances that can cause birth defects in the developing fetus
Maternal alcohol use leads to fetal alcohol syndrome (facial defects, low IQ, neurobehavioral defects)
Nicotine exposure leads to premature birth, low birth weight, and more fetal deaths
These drugs cross the placental barrier and impair fetal brain development
Poor maternal nutrition can impair fetal development
Drug use by father can damage sperm
Alcohol, opiates, cocaine, lead, and various gases are known to damage sperm