Each year in the United States, about 4,000 infants die suddenly of no immediately, obvious cause. About half of these Sudden Unexpected Infant Deaths (SUID) are due to Sudden Infant Death Syndrome (SIDS), the leading cause of SUID and of all deaths among infants aged 1–12 months.
The three most frequently reported causes are SIDS, cause unknown, and accidental suffocation and strangulation in bed. In 2010, 2,063 deaths were reported as SIDS, 918 as cause unknown, and 629 as accidental suffocation and strangulation in bed.
CDC supports new recommendationsissued by the American Academy of Pediatrics (AAP). These new recommendationsaim to reduce the risk of infant death from SIDS as well as death from known sleep-related causes. Read the AAP fact sheet for more information.

Sudden Infant Death Syndrome (SIDS)

Sudden Infant Death Syndrome (SIDS) is defined as the sudden death of an infant less than 1 year of age that cannot be explained after a thorough investigation is conducted, including a complete autopsy, examination of the death scene, and review of the clinical history.
SIDS is the leading cause of death among infants aged 1–12 months, and is the third leading cause overall of infant mortality in the United States. Although the overall rate of SIDS in the United States has declined by more than 50% since 1990, rates for non-Hispanic black and American Indian/Alaska Native infants remain disproportionately higher than the rest of the population. Reducing the risk of SIDS remains an important public health priority.
Expanding Safe Infant Sleep Outreach
The U.S. national campaign to reduce the risk of SIDS has entered a new phase and will now include all sleep-related SUIDs. The campaign, which has been known as the Back to Sleep Campaign, has been renamed the Safe to Sleep Campaign.
Grand Rounds: Public Health Approaches to Reducing U.S. Infant Mortality This powerful session of Grand Rounds highlighted accomplishments and explored public health, clinical, and policy strategies to improve birth outcomes, with special consideration of high risk individuals, families, and communities.
For a medical examiner or coroner to determine the cause of the death, a thorough case investigation including examination of the death scene and a review of the infant’s clinical history must be conducted. A complete autopsy needs to be performed, ideally using information gathered from the scene investigation. Even when a thorough investigation is conducted, it may be difficult to separate SIDS from other types of sudden unexpected infant deaths, especially accidental suffocation in bed.
After a thorough case investigation, many of these sudden unexpected infant deaths may be explained. Poisoning, metabolic disorders, hyper or hypothermia, neglect and homicide, and suffocation are all explainable causes of SUID.

            Sudden Infant Death Syndrome (SIDS) and Vaccines

From 2 to 4 months old, babies begin their primary course of vaccinations. This is also the peak age for sudden infant death syndrome (SIDS). The timing of these two events has led some people to believe they might be related. However, studies have concluded that vaccinations are not a risk factor for SIDS.
With babies receiving multiple doses of vaccines during their first year of life and SIDS being the leading cause of death in babies between one month and one year of age, CDC has led research studies to look for possible linkages. Results from studies below and continued monitoring reassure us about the safety of vaccines.

• The Institute of Medicine (IOM) released a report on Immunization Safety Review: Vaccination and Sudden Unexpected Death in Infancy in 2003. The committee reviewed epidemiologic evidence focusing on SIDS, all sudden unexpected death in infancy, and neonatal death (infant death, whether sudden or not, during the first 4 weeks of life). The committee also looked for possible relationships between SIDS and the individual vaccines diphtheria-tetanus-whole-cell pertussis (DTwP), DTaP, HepB, Hib, and polio; and specific combinations of vaccines. The committee did not find enough evidence to show vaccines cause SIDS.
• A study using Vaccine Safety Datalink (VSD) data, which included children who were covered by a managed care organization health plan, found no association between immunization and deaths in young children. The study investigated deaths in children one month to 7 years of age between 1991 and 1995. Data were analyzed by comparing vaccination histories for each vaccine during the week and month prior to the date of death for each child. Five hundred and seventeen deaths occurred between 1991 and 1995, most (59%) during the first year of life. Of these deaths, the results did not show an association between immunizations and childhood deaths.
• Studies that looked at the age distribution and seasonality of deaths reported to the Vaccine Adverse Event Reporting System (VAERS). SIDS and VAERS reports following DTP vaccination, and SIDS and VAERS reports following hepatitis B vaccination found no association between SIDS and vaccination.
• VAERS also monitors the safety of vaccines. Through VAERS the U.S. Food and Drug Administration carefully investigates all deaths following vaccination that are reported to VAERS.

As a result of the American Academy of Pediatrics' 1992 recommendation to place healthy babies on their backs to sleep, and the success of the National Institute of Child Health and Human Development's Back to Sleep campaign, fewer SIDS deaths are reported. According to "Targeting SIDS: A Strategic Plan:"

• Between 1992 and 1998, the proportion of infants placed to sleep on their stomachs declined from about 70 percent to about 17 percent.
• Between 1992 and 1998, the SIDS rate declined by about 40 percent, from 1.2 per 1,000 live births to 0.72 per 1,000 live births.

These results tell us that most SIDS deaths are due to factors like sleeping on their stomachs, cigarette smoke exposure, and mild respiratory infections.