SIDS caused 1,529 infant deaths in the United States in 2022, making it one component of roughly 3,700 sudden unexpected infant deaths that year. While rates have dropped dramatically since the 1990s, SIDS remains a leading cause of death for babies between one and twelve months old. The overall rate of sudden unexpected infant death (which includes SIDS, accidental suffocation in bed, and deaths from unknown causes) was about 101 per 100,000 live births in 2022.
SIDS vs. Sudden Unexpected Infant Death
SIDS is one category within a broader group called sudden unexpected infant death, or SUID. The three types of SUID are SIDS itself, accidental suffocation or strangulation during sleep, and deaths from unknown causes. In 2022, SIDS accounted for 1,529 of those deaths, accidental suffocation for 1,040, and unknown causes for 1,131. The distinction matters because SIDS is specifically a diagnosis of exclusion: it’s used when a thorough investigation, including autopsy and scene review, cannot identify any other explanation for the death.
When SIDS Risk Is Highest
SIDS clusters heavily in the first half of life. Risk is low in the first few weeks, rises sharply between two and four months, then gradually declines. About 90% of SIDS deaths occur before six months of age. Boys are affected more often than girls, at roughly a 3-to-2 ratio.
There’s also a seasonal pattern. SIDS is more common in winter months. Infants who died in January were roughly twice as likely to have died from SIDS compared to those who died in July or August. The reason isn’t fully established, but researchers have noted that the winter spike in SIDS mirrors the seasonal pattern of infectious diseases in infants, suggesting that winter respiratory infections may act as a trigger in vulnerable babies.
How Rates Have Changed Over Time
The most significant drop in SIDS rates followed the “Back to Sleep” campaign launched in the early 1990s, which urged parents to place babies on their backs rather than their stomachs. Before that campaign, stomach sleeping was common advice. SIDS rates fell substantially in the years that followed. However, the overall SUID rate has plateaued in recent years, partly because some deaths that would once have been classified as SIDS are now categorized as accidental suffocation or unknown cause, reflecting changes in how death scenes are investigated and coded.
Racial and Ethnic Disparities
SUID rates vary dramatically by race and ethnicity, and the gaps have been widening. In 2022, American Indian and Alaska Native infants had the highest rate at about 229 per 100,000 live births. Black infants were close behind at 244 per 100,000, a figure that actually increased from 192 per 100,000 in 2017. Native Hawaiian and Pacific Islander infants also experienced a sharp rise, from 138 to 237 per 100,000 over that same period.
By comparison, white infants had a rate of about 83 per 100,000, Hispanic infants about 62, and Asian infants about 32. These disparities reflect layers of systemic factors: differences in access to prenatal care, housing conditions, exposure to secondhand smoke, and the reach of safe-sleep education campaigns across communities.
How the U.S. Compares Globally
Among developed nations, the United States has one of the higher SIDS rates. In international comparisons, the U.S. has consistently ranked near the top, trailing only New Zealand in some analyses. Countries like the Netherlands and Japan have reported the lowest rates. These differences likely reflect variations in safe-sleep practices, parental leave policies, healthcare access, and how thoroughly infant deaths are investigated and classified.
What Researchers Think Causes SIDS
The leading framework for understanding SIDS is the Triple Risk Model, which describes SIDS as the result of three factors converging. First, the baby has an underlying vulnerability, such as a subtle brain abnormality affecting heart rate or breathing regulation, or a genetic difference that isn’t detectable through routine screening. Second, the baby is in a critical developmental period, typically the first six months, when rapid changes in sleep patterns, breathing control, and blood pressure regulation are happening. Third, an outside stressor pushes the vulnerable baby past a threshold it can’t recover from. That stressor might be sleeping face-down, overheating, or breathing in secondhand smoke.
No single factor causes SIDS on its own. The model explains why most babies exposed to risk factors like stomach sleeping don’t die: they lack the underlying vulnerability. It also explains why SIDS can occasionally happen even when parents follow every guideline, because the underlying vulnerability is usually invisible.
Safe Sleep Practices That Reduce Risk
The American Academy of Pediatrics updated its safe sleep guidelines in 2022, and the core recommendations are straightforward. Place your baby on their back for every sleep, not just at night. Use a firm, flat mattress in a safety-approved crib with only a fitted sheet. No pillows, blankets, stuffed animals, bumper pads, or mattress toppers. Sleep surfaces with an incline greater than 10 degrees are unsafe for infants.
Room sharing without bed sharing is recommended for at least the first six months. This means the baby sleeps on a separate surface near your bed, not in it. Bed sharing significantly increases suffocation risk, particularly on soft surfaces like couches or adult mattresses with pillows and blankets.
Overheating is another avoidable risk factor. Instead of piling on blankets, use a wearable sleep sack to keep your baby warm. Watch for signs of overheating like sweating, flushed skin, or a chest that feels hot to the touch. Skip the hat indoors after the first hours of life. Weighted blankets, weighted swaddles, and similar products should not be used in or near the sleep area.
These measures don’t eliminate SIDS entirely, since some component of the risk involves vulnerabilities that can’t yet be detected or prevented. But safe sleep practices address the environmental stressors in the Triple Risk Model, removing one of the three conditions that need to align for SIDS to occur.