Sudden Infant Death Syndrome (SIDS) is the sudden, unexpected and unexplained death of an infant. SIDS age range is from birth to 1 year of age
Sudden Unexpected Infant Death (SUID) is the sudden and unexpected infant death which may or may not be explained. SIDS is one type of SUID. You may also see SUID referred to as Sudden Unexpected Death in Infancy (SUDI).
In 2015, the United states lost 3700 infants from SUID. This includes 1600 from SIDS, and 900 deaths due to accidental suffocation and strangulation in bed. Most recent SIDS data still shows that SIDS is rare. There are about 40 infants lost to SIDS for every 100,000 live births.
Centers for Disease Control and Prevention. Sudden unexpected infant death and sudden infant death syndrome. Available at https://www.cdc.gov/sids/data.htm Accessed 2/21/2018.
The truthful answer is we don’t know. We know that some infants seem to be more vulnerable to SIDS. SIDS tends to occur at certain stages of neurodevelopment. Also, SIDS is more likely with certain environmental exposures (like overheating or sleeping in any position other than on his/her back).
One leading model is considered the triple risk model, proposed by Filano and Kinney in 1994. This “triple risk model” suggests that SIDS occurs when multiple factors coincide.
In this model, SIDS occurs when a vulnerable infant is exposed to some environmental stressor during a critical stage in development.
“Neuropathologic studies in SIDS victims support the concept that they are not entirely ‘normal’ prior to death, but rather possess underlying vulnerabilities which put them at risk for sudden death. This concept forms a key link in a triple-risk model for the pathogenesis of SIDS proposed by us. According to this model, sudden death in SIDS results from the intersection of three overlapping factors: (1) a vulnerable infant; (2) a critical developmental period in homeostatic control, and (3) an exogenous stressor(s). An infant will die of SIDS only if he/she possesses all three factors; the infant’s vulnerability lies latent until he/she enters the critical period and is subject to an exogenous stressor. According to this model, heterogeneous disorders may make the infant vulnerable to sudden death during the critical period, as potentially exemplified by two previously reported lesions in SIDS brains (arcuate nucleus hypoplasia and subtle hypomyelination). Nevertheless, the triple-risk model does not preclude the possibility that the majority of SIDS deaths will be explained by a single common pathway upon which multiple stressors impinge to produce sudden death during the critical period.”
Reference: Filiano JJ, Kinney HC. A perspective on neuropathologic findings in victims of the sudden infant death syndrome: the triple-risk model. Biol Neonate. 1994;65(3-4):194–197
What causes this intrinsic vulnerability is unclear, but may be related to in-utero environmental conditions, genetics, development or delayed maturation.
In-utero environmental conditions:
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There are racial and ethnic differences in sudden, unexpected infant death and SIDS.
Copied from: Centers for Disease Control and Prevention. Sudden unexpected infant death and sudden infant death syndrome. Available at https://www.cdc.gov/sids/data.htm Accessed 2/21/2018.
We know that SIDS Age peaks at age 1-4 months. In fact, about 72% of SIDS deaths occur during that time period, and 90% occur before 6 months of age. SIDS is rare after 8 months of age.
Modified From: Shapiro-Mendoza CK,
Tomashek KM et. al. Recent national trends in sudden unexpected infant deaths: more
evidence supporting a change in classification or reporting. American Journal of Epidemiology,
Volume 163, Issue 8, 15 April 2006, Pages 762–769. Available here:
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