[Toxicology of reproduction and development. Pregnancy and periods of risks from drugs].

The authors discuss the possibilities of drug interference with the reproductive system and especially during various stages of pregnancy: from the sequence of neurochemical events that condition the release of pituitary gonadotrophines at the level of the central nervous system to late events that may occur during development. After listing the periods of risk, drug-induced changes in the conceptus are illustrated on the basis of data registered in the literature. In this context, it is stressed that the dysmorphogenic effect is limited to the period of differentiation and organogenesis whereas it is becoming more and more obvious that drugs may also have variable effects on other stages of pregnancy where frequently they have specific pharmacodynamic actions on the fetus. The knowledge of these effects may be useful in order to avoid untoward actions on pregnancy or on embryo, fetus, neonate or postnatal development, but may also create a basis for in utero drug treatments of fetal pathologies.