Quiñones-Pérez et al. (2025) compare SUID rates and risk factors among Hispanic and non-Hispanic infants, and associated interactions.

Summary: Researchers analyzed data from nearly 88 million US births between 1996-2017 and found that Hispanic infants had significantly lower rates of Sudden Unexpected Infant Death (SUID) compared to non-Hispanic infants - 0.36 deaths per 1,000 births versus 0.70 per 1,000 - even though Hispanic families often face worse social and economic conditions that typically increase SUID risk. The protection was strongest for babies born to mothers who weren't born in the US (except for Puerto Rican families), and traditional risk factors seemed to operate differently in Hispanic populations. This surprising finding challenges current understanding of what causes SUID and suggests that cultural factors or family practices in Hispanic communities may provide protective benefits that could help reduce infant deaths across all populations if better understood.

Guare et al. (2024) compare prepandemic and intrapandemic rates of SUID and SIDS, assessing for monthly variation.

Summary: Researchers examined national data from 2018 to 2021 to see whether sudden unexpected infant death (SUID) and sudden infant death syndrome (SIDS) rates changed during the COVID-19 pandemic. They found that both SUID and SIDS rates were higher during the pandemic compared with the years before, with the biggest increases occurring from mid-2020 through the second half of 2021. The rise in cases closely followed unusual seasonal spikes in respiratory illnesses like RSV, suggesting that infections may play a role in these deaths. Experts say more research is needed to better understand how infections might contribute to SUID and SIDS and to guide prevention efforts.

Shapiro-Mendoza et al. (2023) examine sudden unexpected infant death (SUID) rates as a group, by cause, and by race and ethnicity

Summary: Although fewer babies died overall in 2020 than in previous years, deaths from sudden infant death syndrome (SIDS) actually went up compared to 2019. Researchers looked at national data on all sudden unexpected infant deaths (SUID)—including SIDS, accidental suffocation, and cases with an unknown cause—to see what changed. They found that the overall number of sudden infant deaths stayed about the same, but the increase in SIDS may have been due to changes in how deaths were classified rather than a true rise in cases. Alarmingly, deaths among Black infants increased, widening the gap between racial and ethnic groups. Fewer than 10 of these deaths were linked to COVID-19. Experts say more attention is needed to understand why this disparity grew and to make sure all families have equal access to safe sleep education and support.

Yong Koh et al. (2022) evaluate genetic contributions to sudden unexpected death in pediatrics (SUDP).

Summary: Scientists studied the DNA of 352 children who died suddenly and unexpectedly, looking for genetic causes of these tragic deaths. They found that about 11% of cases (37 children) had genetic variants that likely contributed to their death, including mutations in genes affecting the heart, brain, and metabolism. The researchers discovered that children who died suddenly were nearly three times more likely to carry rare, harmful genetic variants compared to healthy children, and some had completely new genetic mutations not inherited from their parents. This study provides evidence that genetic factors play an important role in sudden unexpected pediatric deaths, identifying both known disease genes and potentially new ones that could help explain why some children die suddenly without warning.

Keywan et al. (2021) reviews genetic studies that address potential root causes of SIDS.

Summary: Researchers have found that Sudden Infant Death Syndrome (SIDS) isn't caused by a single factor, but rather involves multiple biological problems including issues with metabolism, heart function, brain development, breathing, and infections. This review of genetic studies shows that in some SIDS cases, single gene mutations are directly responsible for the infant's death, suggesting that genetic factors play an important role in this tragic condition. The authors conclude that future research should include more comprehensive genetic testing, study how these genetic changes actually affect the body, and examine parents' genetic information and family medical histories to better understand why some babies die from SIDS.

Brownstein et al. (2018) work to identify an association between SIDS and genetic variants.

Summary: Scientists studied the DNA of infants who died from SIDS (Sudden Infant Death Syndrome) and discovered that 2 babies had genetic changes in SCN1A, a gene normally linked to epilepsy. Neither baby had ever had seizures, but lab tests showed these genetic variants caused the gene to function poorly. This is the first time SCN1A has been connected to SIDS, suggesting that some cases might have a genetic cause related to brain cell communication problems, and indicating that testing for epilepsy genes could help doctors better understand SIDS cases even when babies show no signs of seizures.

Erck Lambert et al. (2018) examine trends in SUID and SIDS, unknown cause, and ASSB from 1990 to 2015 and compare state-specific SUID rates.

Summary: Sudden unexpected infant deaths (SUID) dropped sharply during the 1990s, but progress has slowed in the years since. Researchers looked at national and state-level data from 1990 to 2015 and found that while SUID rates fell nearly 45% in the 1990s, they declined by only 7% from 1999 to 2015. During this time, deaths classified as SIDS went down, but deaths labeled as accidental suffocation more than doubled, suggesting a shift in how these deaths are categorized rather than a major drop in overall cases. Rates varied widely from state to state, with some showing big improvements and others staying the same or even increasing. These findings suggest that states with successful programs could serve as examples for improving infant safety nationwide.

Parks et al. (2017) examine trends in SUID rates and disparities by race/ethnicity since the Back-to-Sleep campaign.

Summary: After the 1994 Back-to-Sleep campaign, sudden unexpected infant death (SUID) rates dropped sharply but have stayed mostly the same since 2000. Researchers studied national data from 1995 to 2013 to see how these deaths varied by race and ethnicity. They found that SUID rates were highest among American Indian/Alaska Native infants, followed by Black infants, though rates for Black infants did decrease over time, narrowing the gap with white infants slightly. Hispanic and Asian/Pacific Islander infants had the lowest rates and saw further declines, widening their differences with other groups. Experts say prevention efforts should focus on groups at highest risk and use culturally tailored approaches to reach different communities.

Hunt et al. (2015) summarize the differing perspectives and approaches in assigning cause of death for sudden unexpected infant deaths.

Summary: Experts say there is ongoing disagreement about how to determine the cause of sudden unexpected infant deaths (SUID), leading to inconsistent reporting across the country. This inconsistency affects not only researchers and medical professionals but also law enforcement, advocacy groups, and grieving families. To address this problem, they recommend forming an international committee of experts to review current practices and create a more unified approach. Such a system would need to consider both babies’ individual risk factors and their environments—like unsafe sleep settings—while staying adaptable as new research emerges.

Malloy & MacDorman (2005) examine post-neonatal mortality rates to determine if SIDS declines are attributed to a shift in how deaths are classified.

Summary: Sudden infant death syndrome (SIDS) is the leading cause of sudden unexpected infant deaths in the U.S., and rates dropped sharply—by more than half—after parents were first advised in 1992 to place babies on their backs to sleep. Researchers looked at national data from 1992 to 2001 to understand these declines and found that while SIDS deaths fell, the overall postneonatal death rate did not improve after 1999. Instead, deaths classified as “unknown cause” or “suffocation” rose during that time, accounting for most of the drop in SIDS. These findings suggest that at least part of the decline in SIDS may be due to changes in how deaths are classified rather than an actual reduction in cases.