teratogens an agent which acts on the developing embryo or fetus to create a structural abnormality or a deviation from normal morphology or function.:1:
FAD Classification of risk :

category A,B,C,D,X :

Category A

.Controlled studies in women fail to demonstrate a risk to fetus in first trimester and the possibility of fetal harm appears remot2.EX.VITAMINS ,FORTIFIED CEREALS AND MILK 3.Balanced electrolyte solutions ,potassium supplements 4.thyroid supplement
.category with fewest drugs
Category B:
1.Either animal reproduction studies have not demonstrated afetal risk but there are no controlled studies in pregnant women or animal studies showed an adverse effect that was not confurmed in controlled studies on pregnant wpmen 2.Multiple medications :Tylenol ,antibiotics ,prozac ,narcotic ,prednisone for asthma
Category C
: .Either animal studies revealed have adverse effects on the fetus and there are no controlled studies in women or studies in women and animals are not available 2.Drugs may be given if the potential benefit justifies the fetal risk
EX:Phenergan ,lorazepam 3.most common category because not all drugs are studied in controlled animal.women pop