A CDC analysis of nearly 4,900 sudden unexpected infant deaths found that at least 73% involved unsafe sleep factors.
Soft bedding, adult beds, and sharing a sleep surface were common circumstances in the cases reviewed.
Researchers say safer sleep environments and more complete death investigations could help improve prevention efforts.
Putting a baby down for a nap or bedtime can feel like one of the most routine parts of parenting. But the environment where an infant sleeps can play an important role in their safety.
A new report from the Centers for Disease Control and Prevention (CDC) examined sudden unexpected infant deaths, or SUIDs, across the United States from 2020 through 2024. The term includes deaths attributed to sudden infant death syndrome (SIDS), accidental suffocation or strangulation in bed, and deaths whose causes remain unknown.
The findings highlight a continuing concern: Many of these deaths involved potentially unsafe sleep conditions. The American Academy of Pediatrics recommends placing babies on their backs to sleep, on a firm, flat surface of their own, without soft bedding.
The CDC estimates that about 3,400 infants younger than 1 year die from SUIDs in the U.S. each year. Understanding the circumstances surrounding these deaths can help researchers and public health officials identify opportunities to prevent future tragedies.
How researchers examined nearly 4,900 infant deaths
For the report, researchers analyzed 4,861 cases recorded between 2020 and 2024 in the CDC's Sudden Unexpected Infant Death and Sudden Death in the Young Case Registry.
The registry collects detailed information from multiple sources, including child death review programs. Unlike standard death records, which may not explain the circumstances surrounding an infant's death, the registry includes information about sleep environments, medical examinations, and death scene investigations.
Researchers reviewed characteristics such as infants' ages, demographics, sleeping positions, bedding, and whether they shared a sleeping surface with another person. They also examined how deaths were classified and which investigative procedures had been completed.
The analysis covered 31 participating jurisdictions, representing approximately 40% of SUID cases nationwide. That means the findings provide an important picture of these deaths but do not represent every case in the country.
What the findings mean for parents and caregivers
Two-thirds of the deaths involved infants between birth and 3 months old. Researchers also found that 78% of infants had soft bedding in their sleep environments, 59% were sharing a sleep surface, and 75% were sleeping somewhere other than a crib, portable crib, or bassinet.
Overall, at least 73% of cases involved unsafe sleep factors. However, that does not mean every death was conclusively caused by an unsafe sleep environment. Some deaths remained unexplained, and the researchers noted that other medical or genetic factors may play a role.
Among the 919 deaths classified as explained suffocation with unsafe sleep factors, soft bedding was the most frequently identified mechanism. Nearly all cases included an autopsy and a death investigation, but important details were sometimes missing. For example, airway obstruction information was unknown or missing in a substantial share of cases.
For families, the findings reinforce the importance of following safe sleep recommendations: place babies on their backs, use a firm, flat, separate sleep surface, and keep blankets, pillows and other soft items out of the sleep area.
The researchers say better documentation and continued investigation of both sleep-related and medical causes could help public health officials develop more effective prevention strategies.