Sudden Infant Death Syndrome

A white crib sits in a bright nursery with yellow walls and striped rainbow rugSudden infant death syndrome (SIDS), also known as crib or cot death, is the name given to the sudden, unexplained death of a seemingly healthy infant. SIDS, which typically occurs during sleep, is the leading cause of death among infants between 1 and 12 months old.

What Is Sudden Infant Death Syndrome?

Although SIDS has been heavily researched, its exact cause remains elusive. Researchers believe it may be connected to abnormalities in the part of the brain that regulates breathing and sleep-wake function, but this has not yet been proven beyond doubt.

Most medical diagnoses are determined through the assessment of symptoms, environmental factors, and/or medical history, but SIDS differs in that it is generally diagnosed after other possible causes of death, such as abuse, accidents, or undiagnosed disorders and conditions, have been ruled out. SIDS, which is unpredictable and thus difficult to prevent, is responsible for around 2500 infant deaths per year in the United States. Infants are considered to be at risk until they are one year old, but most infants who die of SIDS do so within the first six months of age.

Risk Factors for SIDS

Although there is no known cause, years of research have led to the discovery of a number of factors that may indicate a greater risk:

Prenatal risk factors include mother’s age, health, and substance use.

  • Babies born to mothers under the age of 20 have a higher likelihood of dying of SIDS.
  • Babies whose mothers do not receive adequate prenatal care are more likely to die of SIDS than babies whose mothers receive recommended care.
  • Mothers who smoke cigarettes, use drugs, or drink alcohol while pregnant also increase their infant’s risk for SIDS.

Physical and environmental risk factors include birth complications, infections, sleep factors, weather, and smoke exposure.

  • A low birth weight, being one of a multiple-baby birth, or being born premature increase the likelihood of an underdeveloped heart, which increases SIDS risk.
  • Babies who have recently had respiratory infections may experience breathing problems and therefore have a higher risk.
  • SIDS more often occurs in infants who are placed on their stomachs or sides during sleep than in babies who sleep on their backs. Some researchers theorize sleeping on the stomach puts pressure on a baby’s jaw, which pushes on the airway. Others think a breathing disturbance referred to as “rebreathing” (when the same air is breathed in over and over) can occur, leading to a fatal amount of carbon dioxide in the baby’s lungs.
  • Infants put to bed with too much bedding, soft or fluffy bedding, too many layers of clothing, or in the same bed as their parents have an increased risk for SIDS. Although the risk for SIDS increases for infants who sleep in the same bed as their parents, infants who sleep in their own bed in the same room as their parent(s) have a decreased risk of SIDS.
  • Babies exposed to cigarette smoke and other similar airborne toxins are more likely to die from SIDS.
  • Babies who become too hot or too cold while they are sleeping have a higher risk of dying from SIDS.

Biological or genetic risk factors include brain abnormalities, race, sex, and family history.

  • When an infant does not get enough oxygen during sleep, the arcuate nucleus (the part of the brain that controls breathing and arousal from sleep) triggers a response that causes the baby to wake up, change position, and/or cry. Some researchers believe SIDS may occur when the arcuate nucleus does not function properly.
  • Statistics show African-American babies are twice as likely and American Indian babies are three times as likely to die from SIDS than Caucasian babies.
  • Male infants have a higher risk of SIDS than female infants.
  • Babies who have a blood relative who died from SIDS have an increased risk.

Can SIDS be Prevented?

Although there is no way to completely prevent SIDS, much can be done to reduce an infant’s risk. In 1992, the American Academy of Pediatrics launched their Back to Sleep campaign, recommending that parents always put babies sleep on their backs. The SIDS death rate has decreased by 50% since. Medical experts continue to encourage parents to implement the following protective strategies to lower the risk of SIDS:

  • Avoid substance use during pregnancy.
  • Seek out adequate prenatal care and get all recommended immunizations.
  • Keep secondhand smoke and other toxins away from infants.
  • Babies should be put to sleep on their backs. If you use a blanket, it should be tucked firmly under the mattress and should never cover the baby’s head.
  • Choose firm, clutter-free bedding. Avoid using bumper pads, pillows, stuffed animals, etc. in the crib.
  • Breastfeed babies if possible. Hauck et al (2011) found that breastfeeding reduces the risk of SIDS. Additionally, after the breastfeeding connection has been established, give babies a pacifier to sleep with.
  • Put babies to sleep in the same room, but not the same bed.
  • Consult a pediatrician for advice on gastroesophageal issues like GERD or conditions like positional plagiocephaly, also known as a flat spot on the head.

In October of 2016, the American Academy of Pediatrics released new guidelines for SIDS prevention. The new recommendations advise parents to put their infants to bed in the same room, but not in the same bed, for at least the first six months of life.

Conflicting Information about SIDS

Despite decades of study, researchers have been unable to successfully establish a cause for SIDS. The uncertainty surrounding the phenomenon of crib death has created an environment ripe for speculation, disagreement, and controversy, leading to several differing ideas about what triggers this unexpected death in otherwise healthy infants.

One of the more well-known speculated causes is the toxic gas theory. In 2002 the Scottish Cot Death Trust published a study in the British Medical Journal presenting the idea that fungal growth in mattresses (especially mattresses that have been re-used), combined with the materials used to make mattresses flame-retardant, may lead to cot (crib) death. Wrapping the mattress in a polyethylene cover was the solution suggested by researchers. Some professionals support this theory, while others do not, citing insufficient evidence. However, when a mattress-wrapping campaign was adopted in New Zealand (the country with the highest rate of SIDS in the world), the SIDS rate fell drastically: by approximately 85% among non-Maori New Zealanders and by 70% among all New Zealanders.

This is one theory among several, however, and other studies have failed to prove a discernible link between the use of wrapped mattresses and a lowered rate of SIDS.

The Lasting Effects of SIDS

The loss of a child to SIDS is likely to leave a parent traumatized and heartbroken. Feelings of guilt, anxiety, grief, and depression are common among parents who have lost a child in this sudden, unpredictable way. In addition to the grief that comes with losing a child, a SIDS diagnosis can bring with it a medical investigation. Parents may face questioning, assessments, and testing from medical professionals, and they may even be forced to deal with police involvement as other causes of death are ruled out, complicating the grieving process for parents who have just lost their child.

It is highly recommended that parents who have lost a child to SIDS seek emotional support. Mental health outpatient therapy, grief counseling, family therapy, and/or couples counseling may be helpful. Support groups for parents who have lost children to SIDS can also be of benefit to many parents.

The Sudden Infant Death Syndrome Alliance is recommended as a resource for those in need of support.


  1. Information statements. (2016, August 23). Retrieved from
  2. John, T. (2016, October 24). Parents should sleep in same room as newborns to prevent SIDS, doctors say. Time. Retrieved from
  3. Livingston Jr., F. R. (2014, April). Sudden infant death syndrome (SIDS). Retrieved from
  4. Sheppard, J. (2013, November 15). Has the cause of crib death (SIDS) been found?  Retrieved from
  5. Sudden infant death syndrome (SIDS). (2016, June 11). Retrieved from
  6. Sudden infant death syndrome (SIDS). (2015, September 14). NHS Choices. Retrieved from
  7. Tappin, D., Brooke, H., Ecob, R., & Gibson, A. (2002, November 2). Used infant mattresses and sudden infant death syndrome in Scotland: case-control study. British Medical Journal (325)7371.

Last Updated: 10-24-2016

Leave a Comment

By commenting you acknowledge acceptance of's Terms and Conditions of Use.


* Indicates required field.

GoodTherapy uses cookies to personalize content and ads to provide better services for our users and to analyze our traffic. By continuing to use this site you consent to our cookies.