A Resource to Understand and Prevent Sudden Unexpected Infant Deaths

Each year in the United States, thousands of families experience the sudden and unexpected loss of an infant (aged <1 year)—a deeply traumatic event that often lacks clear cause or explanation. The risk of sudden unexpected infant death (SUID) is reduced by placing infants alone on their backs to sleep.1 Although public health campaigns and clinical guidance about safe infant sleep have contributed to a decline in SUID rates, progress has stalled.1 Known risk factors, including sleep environment characteristics, maternal smoking, and preterm birth do not fully explain these deaths. Because the causes of many SUID instances are unknown, additional risk factors likely exist. Families, health care practitioners, and communities want to know the following: “Why and how did these deaths occur?” and “What can be done to prevent future deaths?”To help answer those questions, the Centers for Disease Control and Prevention (CDC) developed the SUID Case Registry,2 a population-based surveillance system that provides systematic data on the circumstances and events surrounding these deaths.3 In participating jurisdictions, detailed information (eg, circumstances at death including the sleep environment and position) is compiled from death scene investigations, autopsy reports, and medical records. This approach provides a more complete picture of the circumstances of death by incorporating medical history and contextual factors, which are not captured in vital records information. Through partnership with the National Institutes of Health, surveillance activities for a subset of participating jurisdictions include monitoring deaths of children of additional ages, working with pediatricians to assess cardiac and neurologic causes of death, and obtaining consent for DNA collection and biospecimen banking, constituting the SUID and Sudden Death in the Young (SDY) Case Registry (hereafter referred to as “Registry”).4Strong collaboration has been central to the Registry’s development and expansion. The Registry was built on the infrastructure of the National Center for Fatality Review and Prevention, including its reporting system and protocols, which include pediatrician participation in multidisciplinary mortality reviews.3 With increasing recognition, resulting from peer-reviewed publications and national conference presentations, the Registry has grown from 5 participating jurisdictions in 2009 to 32 in 2025, representing 40% of all US SUID cases. Since its launch, the Registry has compiled comprehensive, timely, and standardized data on over 13 000 instances of SUID.A critical feature of the Registry is its internally validated algorithm, which systematically groups deaths into explained and unexplained causes.3 Explained deaths, those with identified causes (eg, suffocation), can be studied to advance understanding of risk factors and barriers to safe sleep implementation, and the findings can be used by practitioners to explain risk to families and caregivers. Grouping and quantifying the number of unexplained deaths presents an opportunity to identify death investigation practices that need improvement and explore potential etiologies.5Data collected across multiple jurisdictions allow for detailed examination of SUID case characteristics. An analysis of data from 22 Registry jurisdictions during 2011 to 2020 describe SUID cases without documented unsafe sleep environment factors or that occurred while the infant was awake.5 This finding suggests that a small proportion of deaths may have causes unrelated to the sleep environment, highlighting the need for further etiologic research.5A case-control study using 2016 to 2017 Registry data examined risk factors for SUID with a determined suffocation cause and for SUID attributed to unexplained causes.6 This study confirmed previously established risk factors for unexplained deaths, including prone sleeping, and estimated the magnitude of suffocation risks associated with soft bedding. The findings translate into guidance that is more concrete for caregivers to understand than guidance framed around deaths with unexplained or undetermined causes.A 2020 study identified several SDY etiologies, including respiratory and congenital cardiac diseases, underscoring the importance of careful clinical assessment and follow-up in infants with related risk factors.4 Another study found a correlation between rare epilepsy-related genetic variants and younger age at death in an SDY cohort.7 These findings highlight the importance of systematic classification and detailed characterization of SUID and SDY to better understand underlying mechanisms and inform risk identification. Continued progress depends on access to complete medical histories, comprehensive death investigations, and autopsies—all critical components of the Registry.Although the Registry relies on abstracted child death review (CDR) data and does not involve direct family engagement, participating jurisdictions use Registry data to inform and implement risk-reduction activities. At the national level, Registry data have contributed to development of safe infant sleep recommendations from the American Academy of Pediatrics.1Jurisdictional data have guided state and local initiatives. In Michigan, higher SUID rates among families receiving child protective services prompted required safe sleep training for child protective service workers.8 In Minnesota, Registry data supported a law requiring safe sleep education for licensed childcare workers.9 In Louisiana, recognition of the value of Registry data led to legislation requiring the release of key records (law enforcement, health care, and child and family services) for public health surveillance of child deaths.10In 2023, 10 Registry jurisdictions received additional CDC support to develop sustainable, community-based, SUID interventions reflecting local needs and caregiver perspectives. One example is the Community Partnership Approaches for Safe Sleep—a Chicago initiative in Cook County, Illinois, which convenes families, community leaders, pediatricians, and practitioners to identify and address barriers to safe sleep and develop tailored interventions.11 These efforts address local needs and upstream contributors to SUID, including connections to housing, food, and financial resources.Registry data have also informed activities that directly benefited families of infants who died suddenly. As a result of Registry efforts, 4 jurisdictions (Charleston, South Carolina; Philadelphia, Pennsylvania; and Clark and Washoe Counties, Nevada) have implemented diagnostic genetic testing as part of death investigations for infant deaths of undetermined cause. In some cases, results have identified family members at increased risk for sudden death, prompting clinical monitoring and protective measures. Several jurisdictions have also expanded bereavement support for families following the sudden loss of an infant or child, including grief counseling, resource referrals, and social worker-facilitated support groups.Registry findings strengthen the knowledge base pediatricians and other health care professionals use to counsel and care for families. These findings provide practical information to guide risk-reduction counseling, including safe infant sleep practices, and support development educational resources tailored to communities with high SUID rates. The Registry also fosters partnerships among local, state, and federal entities that expand access to bereavement support and medical evaluations for family members after the sudden loss of an infant or child.The Registry depends on sustained collaboration across systems involved in infant deaths, including clinical care, public health, and public safety. Pediatricians play key roles in this effort. Participation in CDR brings essential clinical expertise to the multidisciplinary process. When pediatricians engage with local or state review teams, case findings are more complete and recommendations better reflect families’ clinical realities. Families experiencing housing instability, limited access to dedicated safe sleep spaces, or cultural practices not well-represented in existing research require tailored counseling beyond standard messaging. Registry-informed, patient-specific guidance can help strengthen that counseling.Since 2009, the Registry has informed national safe sleep recommendations and expanded understanding of when, where, and how instances of SUID can occur (Table 1). This work reflects sustained collaboration among clinicians, investigators, and public health professionals. Continuing this collaboration, through participation in CDR, evidence-informed counseling, and engagement with local public health programs, helps ensure that surveillance findings remain current, representative, and responsive to those they are intended to serve.We would like to acknowledge the Registry’s jurisdictional staff, death certifiers, investigators, and Child Death Review Committee members who contribute data to the Registry; the data team and leadership, Sasha Mintz, Heather Dykstra, Abby Collier, and Esther Shaw, at the National Center for Fatality Review and Prevention (a cooperative agreement funded by the Health Resources and Service Administration) for their support in preparing data from the National Fatality Review Case Reporting System; and our colleagues at the National Institutes of Health and the Registry data coordinating center for their partnership in guiding the sudden death in the young component of the Registry. The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.