Sudden unexpected infant death, or SUID, is a general term for the sudden and unexpected death of a baby younger than 1 year. It includes sudden infant death syndrome, or SIDS, as well as accidental suffocation and strangulation in bed, and infant deaths for which the cause remains unknown.

For this report, the CDC analyzed 4,861 SUID cases that occurred between 2020 and 2024 in 31 jurisdictions around the country that participate in its case registry. This registry provides detailed information about the circumstances surrounding deaths that is not available from death certificates alone.

The main finding is that 73% of the deaths were classified as having unsafe sleep factors. Looking at specific characteristics of the sleep environment, 78% involved soft bedding; 75% occurred on a sleep surface other than a crib or bassinet; 59% involved sharing a sleep surface with another person or animal; and 46% of infants were found sleeping on their stomach or side rather than their back. (These categories overlap, so an infant could have had several of these risk factors.)

There were also substantial racial disparities. Black infants accounted for 38% of the deaths in the registry, and the CDC noted that sudden unexpected infant death disproportionately affects Black and American Indian or Alaska Native infants. The reasons are complex and can include differences in access to resources in order to consistently implement safe sleep practices.