Sudden infant death syndrome (SIDS) is, according to the definition: «The sudden unexpected death of an infant < 1 year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation, including performance of a complete autopsy and review of the circumstances of death and the clinical history.»
Despite the fact that the incidence of Sudden Infant Death Syndrome (SIDS) has been greatly reduced since the growing knowledge of modifiable environmental risk factors and the implementation of education campaigns to avoid such risk factors, SIDS continues to be a leading cause of postneontal infant death in modern society.
Several hypotheses have been postulated to explain the intricate pathogenesis in SIDS, one of which is the triple-risk hypothesis. This hypothesis implies that SIDS only occurs if three independent and necessary factors occur at the same time: a vulnerable developemental stage; predisposing factors (genetic patterns); and a certain trigger event, such as maternal smoking, sleeping position or infection.
Newer research supports the notion that SIDS is a multifactorial disorder, the cause of which is not yet fully understood. Emerging evidence indicates that there is a great number of genetic risk factors, and the interaction between these genetic risk factors and the well known environmental risk factors seems to be of great importance in understanding the pathogenesis of SIDS and to some day be able to determine a child´s actual risk for SIDS.