What is sudden infant death syndrome (SIDS)?

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

NICHD leads federal research on SIDS, including ways to reduce the risk of SIDS. For more information, visit the SIDS A to Z topic.

NICHD also leads the Safe to Sleep® campaign to educate parents, caregivers, and health care providers about ways to reduce the risk of SIDS and other sleep-related causes of infant death, such as accidental suffocation. Visit the Safe to Sleep® website for more information.


  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.
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