What is Sudden Infant Death Syndrome (SIDS)


Sudden infant death syndrome (SIDS) is the unexpected, sudden death of a child under age one in which the cause cannot be determined. It is the number one cause fatalities for infants between one month and one year of age. Its primary causes have not been determined even though there are many theories and studies. Recently many researchers believe that SIDS is due to multiple factors not always related and medical conditions that have as a common denominator a low blood oxygen level and a diminish capability of some babies to wake up after experiencing low blood oxygen levels due to several factors that include hypoxia, sleeping in areas with low ventilation or high concentration of carbon dioxide.

In a new research reported on April 2014, by Professor Roger Byard AO, Marks Professor of Pathology at the University of Adelaide and Senior Specialist Forensic Pathologist with Forensic Science South Australia discovered the presence of a staining of the brain caused by a protein called β-amyloid precursor protein (APP).

This protein is present in babies that had died from asphyxia and babies that had presumably died from SIDS

On another study researchers at Boston Children’s Hospital have found many babies that die “suddenly and unexpectedly” have “underlying brainstem abnormalities and are not all normal prior to death.” The hospital published its findings in the December issue of Pediatrics.

“These abnormalities impair brainstem circuits that help control breathing, heart rate, blood pressure and temperature control during sleep,” the hospital wrote in a press release on the finding of neuropathologist Dr. Hannah Kinney and her team. “The researchers believe [the abnormalities] prevent sleeping babies from rousing when they re-breathe too much carbon dioxide (due to inadequate ventilation), breathe too little oxygen or become overheated (from overbundling).”

Lately, many doctors and researchers believe that the following factors play important roles in many SIDS cases:

  • Inability of the baby's body to detect insufficient oxygen in the blood
  • Inability of the baby to wake up

Epidemiologic Characteristics

The following lists some of the major findings discovered :

  1. SIDS risk is highest when the baby is sleeping.
  2. Prone sleeping position (on the stomach) significantly increases the SIDS risk.
  3. SIDS risk is highest for infant between 1 to 6 months old.
  4. SIDS risk is low for infant under 1 month old.
  5. No evidence of cause of death is found at forensic autopsy.
  6. Winter has a higher risk than summer.
  7. Male has a higher risk than female.
  8. SIDS risk increases with live birth order.
  9. Smoking by parents increases SIDS risk.


Since the exact causes of SIDS have not been determined, there are several recommendations based on the above findings. The recommendations focuses on the sleeping position, sleeping environment, and environment pollutants exposure.

Sleeping position. Place the baby to sleep on the back. This is the most significant recommendation. Since this was announced in 1992, the US SIDS rate has decreased by 40%.

Sleeping environment. The sleeping environment should be comfortable, well ventilated, and safe as the baby may not be able to move away from dangerous situations. The room temperature should be kept at a comfortable level. There should not be anything that may interfere with the baby's breathing even if the baby may turn or move by accident. The following should be avoided:

  • Excessive clothing or blankets result in overheating.
  • Anything that may increase the risk of suffocating the baby, including thick blanket, soft bedding, water bed, soft mattress or pillow.
  • Sleep in the same bed with the baby.
  • Cover the infant's head.

Cigarette smoke exposure. The mother should stop smoking during pregnancy and the baby should be in a smoke-free environment.

Breast feeding. Breast feeding has shown to decrease the risk of SIDS.

Baby sleep monitors

The need of baby sleep monitors for healthy babies has not been established; however this has not stopped many parents from getting one for their peace of mind. There are 4 types of monitors - biometric, movement, video and audio. See Baby Sleep Monitors for more details.