[Risk of medicines in pregnancy: a problem of knowledge transfer with ethical implications].

Drug use in pregnancy is essential and beneficial, but it is needed to check their safety. Available scientific evidence is poor and difficult to interpret. Risk classifications (FDA, ADEC) have shown to be too simple and categorical; they lead to inaccurate perceptions of risk and unfortunate decisions, such as interrumption of medication, or abortion. This has become clear with antidepressants or the antiretroviral efavirenz. Although abortion is not justified, misinformation contributes even more to the problem. Information tends to obviate that not every risk in pregnancy is teratogenic, that the existence of risk does not imply high probability, and that the nature and probability of the risk vary according to the stage.