Sudden unexpected infant death (SUID) is a term used to describe the sudden and unexpected death of a baby less than 1 year old in which the cause was not obvious before investigation. These deaths often happen during sleep or in the baby’s sleep area.

About 3,500 babies in the United States die suddenly and unexpectedly each year. A thorough investigation is necessary to learn what caused these deaths. Sudden unexpected infant deaths include sudden infant death syndrome (SIDS), accidental suffocation in a sleeping environment, and other deaths from unknown causes. Although the SUID rate has declined since 1990s, significant racial and ethnic differences continue. (40)

Sudden Infant Death Syndrome (SIDS): SIDS is identified when the death of a healthy infant occurs suddenly and unexpectedly, and medical and forensic investigation findings (including an autopsy) are inconclusive. SIDS is the leading cause of death in infants up to 12 months old, and approximately 1,500 infants died of SIDS in 2013 (CDC, 2015). The risk of SIDS is highest at 4 to 6 weeks of age. Because SIDS is diagnosed when no other cause of death can be determined, possible causes of SIDS are regularly researched. One leading hypothesis suggests that infants who die from SIDS have abnormalities in the area of the brainstem responsible for regulating breathing (Weekes-Shackelford & Shackelford, 2005). Although the exact cause is unknown, doctors have identified the following risk factors for SIDS:

    • low birth weight
    • siblings who have had SIDS
    • sleep apnea
    • of African-American or Inuit descent
    • low socioeconomic status (SES)
    • smoking in the home

Unknown cause: The sudden death of an infant less than one year of age that cannot be explained because a thorough investigation was not conducted and the cause of death could not be determined.

Accidental suffocation and strangulation in bed: Reasons for accidental suffocation include the following: suffocation by soft bedding, another person rolling on top of or against the infant while sleeping, an infant being wedged between two objects such as a mattress and wall, and strangulation such as when an infant’s head and neck become caught between crib railings.

The breakdown of sudden unexpected infant deaths by cause in 2015 is as follows: 43% of cases were categorized as sudden infant death syndrome, followed by unknown cause (32%), and accidental suffocation and strangulation in bed (25%).
Breakdown of Sudden Unexpected Infant Death by Cause (2015) by the Centers for Disease Control and Prevention resides in the Public Domain .
This stacked bar chart shows sudden unexpected infant death (SUID) rates by cause (sudden infant death syndrome, unknown cause, and accidental suffocation and strangulation in bed) and by race/ethnicity in the U.S. from 2011 through 2014.
Sudden Unexpected Infant Death by Race/Ethnicity, 2011-2014 by the Centers for Disease Control and Prevention resides in the Public Domain .
The combined SUID rate declined considerably following the release of the American Academy of Pediatrics safe sleep recommendations in 1992, which advocated that infants be placed on their backs for sleep (non-prone position). These recommendations were followed by a major Back to Sleep Campaign in 1994. According to the CDC, the SIDS death rate is now less than one-fourth of what is was (130 per 100,000 live birth in 1990 versus 40 in 2015). However, accidental suffocation and strangulation in bed mortality rates remained unchanged until the late 1990s. Some parents were still putting newborns to sleep on their stomachs partly because of past tradition. Most SIDS victims experience several risks, an interaction of biological and social circumstances. But thanks to research, the major risk, stomach sleeping, has been highly publicized. Other causes of death during infancy include congenital birth defects and homicide.

Reducing the Risk of SUID

Health care providers and researchers don’t know the exact causes of Sudden Infant Death Syndrome (SIDS). However, research shows parents and caregivers can take the following actions to help reduce the risk of SIDS and other sleep-related infant deaths:

  • Back to sleep for every sleep. Always place the baby on his or her back on a firm sleep surface such as a crib or bassinet with a tight-fitting sheet.
  • Avoid the use of soft bedding, including crib bumpers, blankets, pillows, and soft toys. The crib should be bare.
  • Breastfeeding is recommended.
  • Share a bedroom with parents, but not the same sleeping surface, preferably until the baby turns 1 but at least for the first six months. Room-sharing decreases the risk of SIDS by as much as 50 percent.
  • The baby should not sleep in an adult bed, on a couch, or on a chair alone, or with anyone else.
  • Avoid baby’s exposure to smoke, alcohol, and illicit drugs.

Co-Sleeping

The location of sleep depends primarily on the baby’s age and culture. Bed-sharing (in the parents’ bed) or co-sleeping (in the parents’ room) is the norm is some cultures, but not in others (Esposito et al. 2015). Colvin, Collie-Akers, Schunn, and Moon (2014) analyzed a total of 8,207 deaths from 24 states during 2004–2012. The deaths were documented in the National Center for the Review and Prevention of Child Deaths Case Reporting System, a database of death reports from state child death review teams. The results indicated that younger victims (0-3 months) were more likely to die by bed-sharing and sleeping in an adult’s bed or on a person. A higher percentage of older victims (4 months to 364 days) rolled into objects in the sleep environment and changed position from side/back to prone. Carpenter et al. (2013) compared infants who died of SIDS with a matched control and found that infants younger than three months old who slept in bed with a parent were five times more likely to die of SIDS compared to babies who slept separately from the parents, but were still in the same room. They concluded that bed-sharing, even when the parents do not smoke or take alcohol or drugs, increases the risk of SIDS. However, when combined with parental smoking and maternal alcohol consumption and/or drug use, the risks associated with bed-sharing greatly increased.

Despite the risks noted above, the controversy about where babies should sleep has been ongoing. Co-sleeping has been recommended for those who advocate attachment parenting (Sears & Sears, 2001), and other research suggests that bed-sharing and co-sleeping is becoming more popular in the United States (Colson et al., 2013). So, what are the latest recommendations? The recommendation is to “share a bedroom,” but not the same sleeping surface. 

Attributions

“Sleep” by Nicole Arduini-Van Hoose, Lifespan Development is licensed under CC BY-NC-SA 4.0

“Lifespan Development: A Psychological Perspective” by Martha Lally and Suzanne Valentine-French is licensed under CC BY-NC-SA 3.0

“Physical Development – Foundations Of Child And Adolescent Psychology” by Troianne T. Grayson, Mary Wuergler, and Michael Konrad, Child and Adolescent Psychology is licensed under CC BY 4.0

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