Treating psychiatric disorders in pregnant women is an important clinical issue. There is an increased number of pregnant women taking psychotropic medication. When used during pregnancy, there might be potential adverse effects of psychotropic drugs in regards to the following: teratogenicity, pregnancy outcome, obstetrical complications, neonatal toxicity, withdrawal syndrome and the offspring's long-term intellectual, behavioral, emotional development. Antidepressant and antipsychotic drugs are generally considered to be relatively safe when used during pregnancy. Benzodiazepine drugs, used for anxiety or insomnia, have a significant risk of birth defects. Lithium and anticonvulsant drugs (with the exception of lamotrigine) should generally be avoided during pregnancy due to congenital malformations. On the other hand, untreated maternal psychiatric illness can also have adverse effects on pregnancy outcome and infant well-being. Available treatments and their potential risks when used during pregnancy should be discussed in the context of the risks of not treating maternal psychiatric illness effectively. The lack of evidence in several areas means that definite conclusions cannot be made about the risks and benefits of all psychotropic drug use in pregnancy.