In the treatment of pregnant women most difficult is the ratio of the degree of benefit to mother and risk to the fetus, because 1 / 3 babies have adverse reactions to drug, and at 3-5% of infants have developmental defects resulting teratogenic effects on the fetus. Therefore, every pregnant woman health worker should explain what side effects may have a drug and whether replace it with others, or whether to keep the pregnancy if the drug need to survive. In view of the fact that the influence of drugs drugs on the fetus has not been fully studied in pregnant women should not appoint any drugs without strict evidence of the fact. If necessary, the appointment medicines pregnant women to their safety should be evaluated risk criteria developed by the U.S. administration to control medicines and food products (FDA).

Group A - drugs that have a large number of pregnant women and childbearing age without any evidence of their impact on the frequency development of congenital anomalies or injurious effect on the fetus.

Group B - drugs that are taken by a limited number pregnant women and women of childbearing age without any evidence of their effect on the frequency of congenital anomalies or injurious effect on the fetus. When this in animal studies found no increase in the frequency of damage fetus or such results were obtained, but does not prove the dependence of the results from the action of the drug.

Group C - drugs that in animal studies have demonstrated teratogenic or embryotoxic effect. It is suspected that they may reversible cause damaging effects on the fetus or newborn (due to the pharmacological properties), but does not cause birth anomalies. Controlled human studies have been conducted.

Group D - drugs that cause or suspected that they cause congenital malformations or irreversible damage to the fetus.

Group X - drugs with high risk of congenital anomalies or Persistent damage to the fetus, because there is evidence of teratogenicity or embryotoxicity in animals and humans. This group is not should be used during pregnancy.