When infants die suddenly and unexpectedly, the causes can be effectively considered using a triple risk model of individual infant susceptibility, developmental vulnerability, and environmental stressors. Sleep practices, particularly prone sleeping and bed sharing, increase the risk posed to vulnerable infants by environmental factors. Infants born prematurely are at increased risk for sudden unexpected death, most likely because of immaturity of respiratory control that causes hypoxemia and long apneas. Infants coming to an emergency department because of a possible cardiorespiratory event that was worrisome to a caregiver should be managed along a spectrum that includes reassurance but is informed by an awareness of potentially serious problems presenting as a nonlethal event.
