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About SUID and SIDS

Understanding the Problem

Learn more about the problem and CDC activities to monitor and reduce sudden unexpected infant death.

About 3,500 US infants die suddenly and unexpectedly each year. We often refer to these deaths as sudden unexpected infant deaths (SUID). Although the causes of death in many of these children can’t be explained, most occur while the infant is sleeping in an unsafe sleeping environment.

Researchers can’t be sure how often these deaths happen because of accidental suffocation from soft bedding or overlay (another person rolling on top of or against the infant while sleeping). Often, no one sees these deaths, and there are no tests to tell sudden infant death syndrome (SIDS) apart from suffocation.

To complicate matters, people who investigate SUIDs may report cause of death in different ways and may not include enough information about the circumstances of the event from the death scene.

Law enforcement, first responders, death scene investigators, medical examiners, coroners, and forensic pathologists all play a role in carrying out the case investigation.

A thorough case investigation includes

  • An examination of the death scene.
  • An autopsy (medical examination of the body after death).
  • A review of the infant’s medical history.

Most SUIDs are reported as one of three types of infant deaths.

Types of SUID

  • Sudden Infant Death Syndrome (SIDS)
    SIDS is defined as the sudden death of an infant less than 1 year of age that cannot be explained after a thorough investigation is conducted, including a complete autopsy, examination of the death scene, and a review of the clinical history. About 1,500 infants died of SIDS in 2014. SIDS is the leading cause of death in infants 1 to 12 months old.
  • Unknown Cause
    The sudden death of an infant less than 1 year of age that is unexplained and is not consistent with or does not meet the criteria for a diagnosis of SIDS.
  • Accidental Suffocation and Strangulation in Bed
    Mechanisms that lead to accidental suffocation include:
    • Suffocation by soft bedding—for example, when a pillow or waterbed mattress covers an infant's nose and mouth.
    • Overlay—for example, when another person rolls on top of or against the infant while sleeping.
    • Wedging or entrapment—for example, when an infant is wedged between two objects such as a mattress and wall, bed frame, or furniture.
    • Strangulation—for example, when an infant’s head and neck become caught between crib railings.

Even after a thorough investigation, it is hard to tell SIDS apart from other sleep-related infant deaths such as overlay or suffocation in soft bedding. While an observed overlay may be considered an explained infant death, no autopsy tests can tell for certain that suffocation was the cause of death.

What Is CDC Doing About SUID and SIDS?

A better understanding of the circumstances and events associated with sleep-related infant deaths may help reduce future deaths. CDC’s activities aim to standardize and improve data collected at infant death scenes and promote consistent reporting and classification of SUID cases. These activities help local and state teams to improve investigation systems by changing practices, policies, and creating data-driven interventions to reduce risk, such as safe sleep education and promotion.

CDC Resources and Activities

  • 1,000 Grandmothers Project
    The 1,000 Grandmothers project reached nearly 200 participants from four tribes, including the Turtle Mountain Band of Chippewa Indians in North Dakota, the Eastern Band of Cherokee Indians in North Carolina, the Hannahville Indian Community (Potawatomie), and the Sault Ste. Marie Tribe of Chippewa Indians, both in Michigan’s Upper Peninsula. Each site used adaptations of selected Healthy Native Babies [PDF - 3.6 MB] materials developed by the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the National Institutes of Health (NIH) and session activities varied by traditional cultures of the tribe. Focus groups, document review, pre- and post- assessments, and key informant interviews were used to evaluate the project, and lessons learned were incorporated into a report and implementation resources. The intergenerational 1,000 Grandmothers project used an evidence-based and culturally appropriate approach to reducing the disparity in SUID rates within the Native American population.  
  • Sudden Unexpected Infant Death Case Registry
    The purpose of the Sudden Unexpected Infant Death Case Registry is to improve states' ability to monitor SUID trends using standardized definitions by improving data completeness, timeliness, and case ascertainment.
  • Sudden Death in the Young (SDY) Case Registry
    The SDY Case registry expands the population of the SUID Case Registry from infancy through adolescence. The SDY registry includes an advanced review where cases are discussed and categorized jointly by pediatric clinical specialists (e.g., cardiologists, neurologists) and forensic pathologists. A blood sample is also collected at autopsy for future research to investigate the cause of death. For more information, see Frequently Asked Questions about the Sudden Death in the Young Case Registry.
  • Sudden Unexplained Infant Death Investigation Reporting Form (SUIDIRF)
    The SUIDIRF was designed to help investigative agencies to better understand the circumstances and factors contributing to unexplained infant deaths.
  • Sudden Unexplained Infant Death Investigation Training Resources
    CDC collaborated with organizations and subject matter experts to create training materials for investigators and instructors who investigate infant deaths.
  • Protect the Ones You Love Initiative
    CDC’s National Center for Injury Prevention and Control launched the Protect the Ones You Love initiative to raise parents’ awareness about the leading causes of child injury in the United States (including suffocation) and how they can be prevented.
  • Pathologic Evaluation of Sudden Unexplained Infant Death
    CDC’s Infectious Diseases Pathology Branch in the National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) evaluates biospecimens from infants whose deaths cannot be explained. State health departments, US physicians, and non-US physicians can submit specimens for deaths where clinical or laboratory information suggests potential infection.
  • National Center for Health Statistics- National Vital Statistics System
    The National Vital Statistics System publishes information about infant deaths, which may be used to monitor causes of death (such as SIDS) among infants younger than 1 year of age in the United States, Puerto Rico, the Virgin Islands, and Guam.
  • PRAMS (Pregnancy Risk Assessment Monitoring System)
    PRAMS collects state-specific, population-based maternal and infant health data from women 2 to 6 months after delivery, including infant sleep practices.
	front page of SUID Fact Sheet

SUID Fact Sheet

Learn more about SUID and CDC’s SUID Case Registry. [PDF - 197 KB]

	Image of a baby sleeping with text Safe to Sleep

Safe to Sleep

CDC collaborates with the National Institutes of Health in its Safe to Sleep campaign, formerly known as the Back to Sleep campaign. Safe to Sleep has outreach and education activities aimed at reducing infant death from sudden infant death syndrome (SIDS) and other sleep-related infant deaths.