Every child’s life matters. Every unanswered loss deserves our attention.
Each year, thousands of infants and children in the United States die suddenly, leaving families facing profound grief—and, in many cases, no clear explanation.
At the Isabel Davis Center for Safe Children, we bring together scientific research, careful investigation, practical prevention, and compassionate family support to address these losses. Our work begins with a commitment: to learn more from what has happened, support the families living with its consequences, and develop better ways to protect children.
The scale of the problem
In 2024, the United States recorded 3,397 sudden unexpected infant deaths (SUID). Of these, 2,450 were classified as sudden infant death syndrome or unknown cause; another 947 were classified as accidental suffocation and strangulation in bed. These categories are grouped together for public health monitoring, but they do not all mean the same thing. Source: CDC
Unexplained deaths also occur after infancy. The SUDC Foundation estimates 418 sudden unexplained deaths among children and young people aged 1–19 in 2024, using mortality records to estimate a problem that is difficult to count consistently. Source: SUDC Foundation
These numbers represent children whose futures were lost and families whose lives changed permanently. They also reveal a substantial gap in our ability to explain, predict, and prevent sudden death.
Understanding the terms
Families may encounter several different terms after a sudden death. Understanding them helps explain both what is known and what remains uncertain.
| Term | What it means |
|---|---|
| Sudden unexpected infant death — SUID | An umbrella term for the sudden death of a baby younger than 1 year when the cause is not immediately apparent. An investigation may identify a cause, or the death may remain unexplained. |
| Sudden infant death syndrome — SIDS | The death of an infant younger than 1 year that remains unexplained after a thorough investigation, including an autopsy, examination of the death scene, and review of the clinical history. |
| Sudden unexplained death in childhood — SUDC | A sudden death after the first birthday that remains unexplained after a thorough investigation. |
SIDS is included within SUID. A death classified as accidental suffocation is also included in the combined SUID statistics, but it is not SIDS. Sources: CDC, SUDC Foundation
In Texas, SUID deaths among children under the age of one outpace all child deaths from ages 0-17 from motor vehicle crashes, homicide, suicide, or cancer from 2018-2023. SUID remains a primary source of lost life and years throughout the United States.
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The terminology serves important purposes. Yet a classification alone cannot convey every observation, unanswered question, or experience associated with a child’s death.
Prevention has made a difference. Further progress requires more understanding.
Safe-sleep recommendations and public education helped drive a major decline in sudden unexpected infant deaths during the 1990s. The combined U.S. SUID rate fell from approximately 155 deaths per 100,000 live births in 1990 to 94 in 1999. Source: CDC
The decades that followed have not brought another sustained decline of that magnitude. In 2024, the rate was 93.6 deaths per 100,000 live births. Individual years have fluctuated, but the remaining burden shows how much work is still needed. Source: CDC trends, 1990–2024
We must continue helping families reduce known risks. We must also investigate why some infants are especially vulnerable, how that vulnerability develops, and whether future interventions could protect them.
All analyses and figures were generated by Dr. Savannah Lusk.
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Why can a seemingly healthy child be vulnerable?
Breathing, heart function, and waking from sleep depend on biological systems that develop rapidly during early life. Researchers are investigating whether differences in these systems can make some infants less able to respond to a dangerous challenge.
One widely used framework for understanding SIDS is the triple-risk model. It considers the interaction of:
- An underlying vulnerability, such as a difference in the systems controlling breathing or waking.
- A sensitive period of development, when those systems are changing.
- An outside stressor, such as a hazardous sleep condition or smoke exposure.
This is a framework for investigating how SIDS may occur, rather than a test that determines what happened to an individual child. Source: NIH Safe to Sleep
The scientific challenge is to understand how these factors interact and why their effects may differ from one infant to another.
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A risk factor and a cause are different kinds of information
A risk factor tells us that a circumstance is associated with a greater chance of an outcome. Establishing a cause requires evidence about what actually produced that outcome.
For example, finding a hazardous sleep condition is important for prevention and investigation. Its presence alone does not establish the mechanism of death in every case. This distinction is recognized in published guidance discussed by CDC researchers. Source: Sudden Unexpected Infant Deaths: 2015–2020
Careful research must examine both environmental circumstances and biological vulnerability. Families need clear risk-reduction guidance, while science must continue investigating the questions that guidance cannot yet answer.
Why an investigation may still leave unanswered questions
A thorough investigation can bring together medical history, observations from the scene, autopsy findings, and information from caregivers. Each contributes something important.
However, the information available is not always complete. Some biological processes cannot be reconstructed after death. Certain specialized tests are not routinely available, and the meaning of a finding may remain uncertain.
The information must also move through systems designed for different purposes. Death certificates support official determinations and national statistics. Child death review and surveillance systems provide additional information for prevention. Laboratory research asks a further question: what biological process could explain these observations?
Different classification practices can complicate comparisons across places and over time. Even a detailed case record may contain observations that are difficult to compare when they remain in separate reports or narrative descriptions. Source: Understanding three approaches to reporting sudden unexpected infant death in the USA
Our research asks how the information available combines to create a fatal failure in natural cardiorespiratory functions.
The figure was created by Dr. Lusk; permission is required for reuse of any kind.
Prevention must be practical and accessible
The burden of sudden unexpected infant death is not shared equally. CDC data show substantial differences across racial and ethnic groups, with particularly high rates among American Indian or Alaska Native and Black infants. These population-level statistics describe disparities; they do not explain an individual child’s biology or circumstances. Source: CDC
Effective prevention requires listening to what families need to put recommendations into practice. Access to a suitable sleep space, healthcare, understandable information, and dependable support can shape the options available to caregivers.
At IDCSC, community conversations help connect prevention knowledge with everyday realities. Our outreach includes safe-sleep education and connections to practical resources, with attention to language, culture, and the barriers families describe.
Families need support while the search for answers continues
For a bereaved family, scientific uncertainty can become part of daily life. Questions may continue long after an investigation closes. Parents, siblings, grandparents, and other loved ones may need different kinds of support at different times.
We believe families deserve to be heard, treated with dignity, and supported whether or not a definitive explanation becomes available.
IDCSC offers personalized remembrance items at no cost and helps families find bereavement resources. Family support does not require research participation. Families who wish to explore research opportunities should be able to do so with clear information and respect for their choices.
How the Isabel Davis Center responds
Our center connects work that is often carried out in separate settings.
We strengthen investigation and learning.
Training supports thorough documentation, respectful communication with families, and information that can contribute to child fatality review and research.
We investigate biological mechanisms.
Genetic tools, laboratory models, and measurements of breathing and heart function help us test how potential vulnerabilities affect protective responses.
We pursue earlier recognition of vulnerability.
Research into newborn blood spots and physiological patterns asks whether biological signals could eventually help identify infants who need additional protection. These efforts are research toward future tools, not an established screening service.
We support prevention and families today.
Community education, resource connections, professional training, and remembrance services address needs that exist now.
The long-term aim is to connect these efforts: preserve better information, ask more precise questions, test possible explanations, and develop interventions that can prevent future losses.
Help us move this work forward
A family seeking support, an investigator documenting a scene, a clinician recognizing an unanswered question, a researcher testing a mechanism, and a community partner sharing resources each bring something valuable to this effort.
We welcome people across disciplines who want to help protect children and support families.
Our purpose is to build the understanding and practical support that make many more birthdays possible.
Explore our research
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To discuss a collaboration, contact idcsc@bcm.edu.
Statistics reflect the source years shown. All Figures and Images require permission before any reuse or copying.
Page reviewed September 2026.