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What is sudden infant death syndrome (SIDS)?

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Sudden infant death syndrome (SIDS) is the sudden death of an infant younger than 1 year of age that is still unexplained after a complete investigation. This investigation can include an autopsy, a review of the death scene, and taking complete family and medical histories.1

Data from the Centers for Disease Control and Prevention show that 2,226 infants died from SIDS in 2009 (the most recent year for which data are available).2

SIDS is the leading cause of death in children between 1 month and 1 year of age.3 The majority (90%) of SIDS deaths occur before a child is 6 months old, with most occurring between 1 and 4 months.4

How can parents and caregivers reduce the risk for SIDS?

Currently, there is no known way to completely prevent sudden infant death syndrome (SIDS), but there are ways to reduce the risk.

The single most effective action that parents and caregivers can take is to place babies to sleep on their backs for all sleep times. Research shows that5:

  • Sleeping on the stomach carries the highest risk for SIDS—between 1.7 and 12.9 times the risk of sleeping on the back.
  • Lying on the side to sleep also increases the risk of SIDS. It is unstable, and babies can easily roll over to their stomachs.
  • Sleeping on the back carries the lowest risk for SIDS and thus is safest.

For more information about SIDS and ways to reduce the risk for SIDS, visit SIDS Health Topic.


  1. Willinger, M., James, L. S., & Catz, C. (1991). Defining the sudden infant death syndrome (SIDS): Deliberations of an expert panel convened by the National Institute of Child Health and Human Development. Pediatric Pathology, 11, 677–684. [top]
  2. Kochanek, K. D., Xu, J., Murphy, S. L., et al. Deaths: Final Data for 2009. National vital statistics reports; vol 60 no 3. Hyattsville, MD: National Center for Health Statistics. 2012. Retrieved on February 22, 2013, from http://www.cdc.gov/nchs/data/nvsr/nvsr60/nvsr60_03.pdf (PDF - 3.11 MB) [top]
  3. Centers for Disease Control and Prevention. (2012). Infant health. Retrieved June 1, 2012, from http://www.cdc.gov/nchs/fastats/infant_health.htm [top]
  4. American Academy of Pediatrics. (2011). SIDS and other sleep-related infant deaths: Expansion of recommendations for a safe infant sleeping environment. Pediatrics, 128, 1030–1039. Retrieved June 6, 2012, from http://pediatrics.aappublications.org/content/128/5/e1341.full External Web Site Policy [top]
  5. American Academy of Pediatrics Task Force on Sudden Infant Death Syndrome. (2005). The changing concept of sudden infant death syndrome: Diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk. Pediatrics, 116, 1245–1255. [top]

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Last Updated Date: 06/24/2013
Last Reviewed Date: 04/12/2013
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