Sudden infant death syndrome (SIDS) refers to the unexpected, unexplained death of a child less than one year old. SIDS is rare during the first month of life. It peaks at 2 to 4 months of age, then gradually decreases.


Experts do not know why some infants suddenly die. Research hopes to find a preventable cause. Many theories exist. It is likely that research will reveal that among babies who die of SIDS there are several different, but important causes. Some suggested causes include:

  • Abnormalities in a section of the brain that controls breathing during sleep and waking
  • Abnormalities in the control of heart rhythm
  • Changes in how serotonin, a neurotransmitter, functions in the brain
  • Changes in some components of the immune system
  • Inadequate arousal response to breathing obstruction or asphyxia (a lack of oxygen or excess carbon dioxide in the body caused by interruption of breathing; may cause unconsciousness)


Area of the brain involved in regulation of breathing.
© 2009 Nucleus Medical Art, Inc.

Risk Factors

Factor is something that increase the chance of SIDS include:

  • Infant's age: less than 6 months old
  • Low birth weight
  • Fetal growth retardation
  • History of SIDS death in a sibling
  • History of an acute life-threatening event
  • Previous incident of unexplained severe apnea (when breathing is repeatedly interrupted) requiring resuscitation
  • Sleeping on the stomach or side rather than back
  • Other risk factors are more general and include:
    • Mother's age: younger than 20 during first pregnancy
    • Black, Native American, and Alaskan Native families
    • Poverty may play a role
    • Sex: male
    • Smoking during pregnancy or in a house where the baby is sleeping
    • Alcohol, opiate, or cocaine use during pregnancy
    • History of anemia]]> or a ]]>urinary tract infection]]> while pregnant
    • No or late prenatal care
    • Premature birth
    • Recent infection and/or fever
    • Cold weather in late fall or winter
    • Overheating
    • Low socioeconomic status or low level of education
    • No pacifier use at bed time



A baby that dies of SIDS typically appears healthy. He or she may have had a cold]]> or gastrointestinal infection in the two weeks prior to death. There usually are no warning signs that a baby is about to die of SIDS.


All possible illnesses and causes of death must be ruled out before a diagnosis of SIDS is made. A complete investigation will take place including:

  • Autopsy
  • Assessment of the death scene
  • Review of the baby's and family's medical histories


Emergency medical personnel should be called as soon as the infant is discovered not breathing. Infant CPR should be started immediately. Seek immediate medical care even if the baby starts breathing again. The cause of the incident should be fully evaluated. Families may need grief counseling after the death. Some parents find support groups helpful.


There is no way to predict which infants will die of SIDS. Several actions may help you lower your child's risk of SIDS:

During pregnancy:

  • Get prenatal care early and regularly.
  • Do not smoke or use drugs while pregnant.

After birth:

  • Put the baby down to sleep on his or her back. Do not allow a young baby to sleep on his or her stomach or side. Back to sleep practices have significantly reduced the occurrence of SIDS in many countries. Ask your doctor for more information about positioning your baby for sleep.
  • Other factors that may help reduce SIDS risk include:
    • Provide a firm crib mattress.
    • Do not place blankets, a comforter, pillow, or sheepskin under the baby.
    • Do not let the baby sleep on a waterbed.
    • Remove soft, stuffed toys from the bed.
    • Keep the baby's room at a comfortable temperature (68°F-72°F).
    • Do not overdress the baby.
    • Allow pacifier use during nap time and bedtime.
    • Do not cover the baby's head or face.
    • Avoid overheating.
    • Do not smoke in the house, or quit entirely.
    • Take the baby for regular medical care.
    • Have your child immunized at the recommended times.
    • Learn infant CPR.
    • Allow the infant to sleep in their crib in the same room you sleep in (but do not let them sleep in the same bed)
  • The American Academy of Pediatrics does not recommend use of an apnea monitor solely for prevention of SIDS. It has not been shown to make a difference.

Make sure anyone else caring for your child is also aware of these recommendations, especially that the baby should be placed on his or her back for sleeping.