Toxicological aspects of perinatal analgesia.

Perinatal exposure to analgesics and anesthetics is responsible of acute effects which are relatively easy to detect and, accordingly, a large number of clinical and experimental observations has been gathered. On the contrary, the possible long term consequences of perinatal administration of these drugs have recently become the object of great interest. It is possible, infact, that perinatal exposure to neurotropic agents may lead to long term neuropsychopharmaco-logical effects that outlast the effective presence of the drug in the newborn. The conceptual framework of this hypothesis is provided by the modern concept of neuroplasticity, according to which early life experiences that serve to set the operating characteristics of the brain may represent the target of pharmacologically-induced changes. Clinical studies have already provided evidence of the association between labour analgesia and the development of maladaptive behaviour in adult life, while experimental studies suggest that maternal care can actively program differences in gene expression through stable effects on the epigenome. Although they require to be confirmed by further studies possibly performed on wider cohorts, these results suggest caution in the use of obstetric pain relief methods that permit substantial passage of drugs through the placenta.