While you are pregnant, almost everything you eat, drink or smoke passes through your body to your baby. That is why drugs taken during pregnancy can be harmful to your baby. Legal drugs include cigarettes and alcohol. Cigarettes and other tobacco products contain nicotine, a highly addictive substance. Babies whose mothers smoke during pregnancy are more likely to be small at birth or to be born prematurely.
Alcohol can cause mental retardation, problems with growth, and abnormal facial features.
Prescription medicines can also cause problems. Some prescription acne medicines can cause birth defects. So can some medicines used to treat seizures. The antibiotic tetracycline, can cause changes in the baby's teeth and bones if taken late in pregnancy. Tranquilizers can be addictive to the baby and the mother.