What Is Sudden Infant Death Syndrome?

By Tiffany Tseng. May 7th 2016

Sudden infant death syndrome, often shortened as SIDS, can be a sad and devastating situation. It is defined by sudden and unexpected death of infants less than one year old, with causes that are not clear at first. Sudden infant death syndrome is also commonly referred to as “crib death,” due to the reason that it often takes place while the infant is sleeping.


It should be noted that sudden infant death syndrome is different from sudden unexpected infant death (SUID) in that the former is due to unexplainable causes. The latter, on the other hand, will have explanations post-investigation. Common causes for SUID may include accidental poisoning, suffocation, neglect, homicide, hypothermia and other medical disorders unearthed upon medical examination.

Why Does SIDS Occur?

According to the Center for Disease Control, there are more than 4,500 cases of SIDS annually. Fortunately, cases of crib death in the United States have declined about 50 percent since 1990, and public health is making advances in SIDS research. The exact cause of crib death often remains unexplained, even after a thorough investigation, autopsy, or health assessment of the infant. While medicine and science may not be able to explain the exact cause of sudden infant death syndrome, it is important for the parents to realize that it is not their fault, or anyone else’s, that SIDS happened.

Probable Causes

The exact cause of sudden infant death syndrome is unknown, as it may be difficult to separate SIDS from other causes of infant death, such as suffocation or hypothermia.  There are several probable causes doctors believe can cause the incident:

  • Brain abnormalities. The area that controls breathing and arousal from sleep may be defected.
  • Low birth weight due to premature birth or multiple births. There is a chance that the infant’s brain has not fully developed, thus resulting in decreased auto responses, such as breathing and heart rate.
  • Respiratory infections. Infants with a bad cold are more at risk for SIDS, as breathing troubles can be worse during sleep.
  • Sleeping on the stomach or side. Infants who do not sleep on their backs have more troubles breathing normally during sleep.
  • Sleeping on a soft surface. Sometimes, fluffy blankets or a soft water bed can unintentionally block a baby’s breathing.
  • Sleeping with parents, or a full crib. Infants that sleep in a crib full of pillows, toys, and stuffed animals have a higher chance of blocked breathing.

Risk Factors

Some risk factors for sudden infant death syndrome include:

  • Being of African American descent.
  • Being of American Indian and/or Alaska Native (Eskimo) descent.
  • Infants with respiratory infections or illnesses.
  • Male infants have a higher risk of SIDS than female infants.
  • Infants during the second and third months after birth are the most vulnerable.
  • Infants who have a family history of SIDS, probably due to genetic links and defects.
  • Infants with mothers under the age of 20.
  • Infants with parents that smoke cigarettes, participate in recreational drug use, or abuses alcohol.
  • Infants of mothers who had insufficient prenatal care prior to birth.


Here are some tips parents can employ to try and lessen the risk of SIDS.

For mothers-to-be:

  • Schedule regular prenatal visits with an obstetrician.
  • Do not smoke, drink alcohol, or use recreational drugs during pregnancy and after birth.
  • Stay away from places of second hand smoke.
  • Adopt a healthy, nutritious diet during pregnancy.
  • Wait at least one year between infants to get pregnant again, to reduce the risk of SIDS for the first infant.

For parents:

  • Place the infant on his or her back for sleeping, not on the stomach or side.
  • Make sure the crib or the sleeping surface is firm.
  • Do not fill the crib or the infant’s sleeping area with pillows, linen, blankets, toys, or stuffed animals. Such extras can be safe for infants older than one year old, as they will be past the age with the highest risk of SIDS.
  • Keep the crib in the same room, but not the same bed. That way, you can keep an eye on the crib at all times.
  • Breastfeed the infant for as long as you can. Studies have shown breastfeeding to help reduce risks of SIDS.
  • Similar to the idea of breastfeeding, offer a pacifier at nap time and bed time. If the pacifier falls out after the baby is asleep, it is fine to leave it there.
  • Schedule regular doctor visits for your baby to ensure optimal health at all times.
  • Keep your infant away from second hand smoke.
  • Keep your baby comfortably cool. Babies that feel hot when sleeping may move around during sleeping and increase the risk of suffocation.
  • Do not cover the infant’s head while he or she is sleeping.


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