Sudden Infant Death Syndrome (SIDS)

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Sudden Infant Death Syndrome (SIDS)

Topic Overview

What is sudden infant death syndrome (SIDS)?

Sometimes a baby who seems healthy dies during sleep. This is called sudden infant death syndrome or SIDS. SIDS is also known as crib death.

In most cases, a parent or caregiver places the baby down to sleep and returns later to find the baby has died. It’s no one’s fault. SIDS can happen even when you do everything right.

Although SIDS is rare, it is one of the most common causes of death in babies between 1 and 12 months of age. Most babies who die of SIDS are between the ages of 2 and 4 months.

What causes SIDS?

Doctors don't know what causes SIDS. It seems to happen more often in premature and low-birth-weight babies. It also is seen more often in babies whose mothers did not get medical care during the pregnancy and in babies whose mothers smoke. SIDS may also be more likely in babies who were part of a multiple pregnancy (for example, twins or triplets) or whose mothers are younger than 20.

When babies sleep on their bellies, they may not breathe well. Not too long ago, side sleeping was said to be okay. But babies placed on their sides can easily roll onto their bellies and could have trouble breathing.

Researchers are studying the possibility that SIDS may be caused by problems with how well the brain controls breathing, heart rate and rhythm, and/or temperature during the first few months of life. More research on this is needed.

What are the symptoms?

SIDS has no symptoms or warning signs. Babies who die of SIDS seem healthy before being put to bed. They show no signs of struggle and are often found in the same position as when they were placed in the bed.

How is SIDS diagnosed?

SIDS is named the cause of death only when no other cause is found. To find out why a baby died, medical experts review the baby's and parents' medical histories, study the area where the baby died, and do an autopsy.

What can you do to reduce the risk of SIDS?

There is no sure way to prevent SIDS, but doing certain things may help protect a baby:1, 2

  • The most important thing you can do is to always place your baby to sleep on his or her back rather than on the stomach or side.
  • Don't smoke while you are pregnant. Also, do not let anyone smoke around your baby after he or she is born.
  • For the first 6 months, have your baby sleep in a crib in the same room where you sleep.
    • Make sure the baby sleeps on a firm mattress (with a fitted sheet).
    • Don't put anything in the crib that a baby can pull over his or her head, such as blankets, bumper pads, comforters, stuffed toys, or pillows.
    • Keep the room warm enough so that your baby can sleep in lightweight clothes without a blanket.
  • Consider offering your baby a pacifier at nap time and bedtime. This may help prevent SIDS, though experts do not know why. If you breast-feed, wait until your baby is about a month old before you start giving him or her a pacifier.

Make sure your baby’s caregivers know what you expect them to do. Don't assume they know what to do to help reduce the risk of SIDS.

Frequently Asked Questions

Learning about sudden infant death syndrome (SIDS):

Being diagnosed:

End-of-life issues:

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Sudden infant death syndrome (SIDS) has no symptoms or warning signs. Babies who die of SIDS:

  • Cannot be revived (resuscitated).
  • Seem healthy before being put to bed.
  • Show no signs of having struggled. The baby is often found in the same position as when he or she was put to bed.

Very few babies who die of SIDS may have had one or more apparent life-threatening events (ALTE).3 During ALTE, a baby has abnormally long pauses in breathing (longer than 20 seconds). The skin changes colour (bluish and blotchy) or becomes pale, and the body stiffens and then goes limp. The baby may also choke or gag. Machines (apnea monitors) that are commonly used to detect these periods of interrupted breathing have not been shown to prevent SIDS.

Examinations and Tests

No diagnostic examination or test can predict whether a baby is likely to die of sudden infant death syndrome (SIDS).

A thorough investigation is conducted after every suspected SIDS incident. The baby's funeral can be held before the report is complete. Examinations and tests related to the investigation include:

  • An autopsy performed by a medical examiner (preferably one experienced in identifying diseases and causes of death in babies). This may include X-rays, blood tests, and tissue cultures to rule out other causes of death.
  • Questions regarding the parents' and the child's medical histories.
  • A careful examination of where the baby died.

Early Detection

There are no known tests that can determine whether a baby may die of SIDS, even for those who are suspected of having a higher risk.

Machines called apnea monitors have been used on some babies believed to be at high risk for SIDS. These machines sound an alarm when they detect a lapse in breathing. But monitoring a baby's breathing while asleep has not been shown to prevent SIDS.

Treatment Overview

There is no treatment for sudden infant death syndrome (SIDS). A baby's death from SIDS cannot be predicted or prevented. But you can take precautions that may reduce the chance that your baby might die of SIDS. The single most important thing you can do is place your baby to sleep on his or her back.

There are products that are marketed to help prevent SIDS, such as ventilated mattresses. But no mattress or other product has been proved to lower the risk of SIDS.


Remember, sudden infant death syndrome (SIDS) is rare. Don't let your fear of SIDS keep you from enjoying your baby.

Studies have found that some risk factors are associated with SIDS, although the relationships are not entirely clear. You can take the following precautions that may help reduce your baby's risk of SIDS:4

  • Do not smoke, and take care of yourself when you are pregnant. During pregnancy, you can lower your baby's risk for SIDS by getting prenatal health care and taking general precautions. Also, do not allow anyone to smoke around your baby after he or she is born. Second-hand smoke also increases your baby's risk of SIDS.
  • Always place your baby down to sleep on his or her back. This is the safest sleep position for a baby. SIDS occurs less in the countries that have urged parents to place babies younger than 1 year old on their backs to sleep. It is important to follow these guidelines every time your baby sleeps. Children who are unaccustomed to sleeping on their stomachs and are then placed on their stomachs for sleep may be at an even higher risk for SIDS.3 Unless your doctor advises otherwise, do not place your baby to sleep on his or her side or stomach.
  • For the first 6 months, place your baby to sleep in a crib in the same room you sleep in. (You can use a cradle or bassinet.) The Canadian Paediatric Society recommends that for the first year of life, the safest place for babies to sleep is in their own crib .1 If you do sleep together, take precautions to make bedsharing safer. Do not ever share a bed with your baby if you smoke, have had alcohol, used medicine that makes you sleep very soundly (sedatives), or used illegal drugs. Never sleep with a baby on a couch or armchair.
  • Use firm bedding materials, including a firm mattress. Make sure the baby sleeps directly on a firm mattress with a fitted sheet.
    • Choose a crib, cradle, or bassinet that meets all the safety standards set by the Canadian Government. (Baby beds that attach to the side of the parents' bed have not yet been tested enough to have set safety standards.)
    • Don't use sleep positioners. And don't put anything else in the crib with your baby. A baby may pull items like blankets, comforters, stuffed toys, or pillows over his or her head and increase the chance for SIDS.
    • If a sheet or blanket is needed for warmth, tuck it into the bottom of the crib. Place your baby so his or her feet touch the end of the crib where the sheet is tucked in. Make sure the sheet or blanket does not reach higher than the baby's chest.
  • Avoid overheating your baby or the room where the baby sleeps. Keep the room where your baby sleeps warm enough [around 18°C (65°F)] so that he or she can sleep with light clothing without needing covers. Usually, the temperature is about right if an adult can wear a long-sleeved T-shirt and pants without feeling cold. But make sure your baby does not get too warm. Putting extra blankets or clothes on your baby in winter can increase the chance that he or she gets too warm. Your baby is likely too warm if he or she sweats or tosses and turns a lot.
  • Give your baby a pacifier at nap time and bedtime. 5 This may help prevent SIDS for reasons that experts do not yet fully understand.
    • If you breast-feed, wait until your baby is about 1 month old before you offer a pacifier. Pacifiers sometimes confuse a newborn baby and can make breast-feeding more difficult.
    • Don't worry about putting the pacifier back into your baby's mouth after he or she has fallen asleep.
    • Don't force your baby to use a pacifier if he or she does not want it.
  • Talk with your child care providers and babysitters about these precautions. Explain in detail on the first day of child care (or before) what you expect the staff to do. Do not assume that your child care providers know what things might lower the chance of SIDS. About 20% of SIDS deaths occur in child care settings.6

Don't rely on home monitors or other devices marketed as a way to reduce your baby's risk of SIDS. These items have not been tested enough to prove they work.

Help your baby develop a normal head shape

The back of your baby's head may get a little flat from always placing him or her to sleep on the back. Usually, the flat area is not very noticeable. Your baby's head shape will return to normal after he or she can sit and crawl. But sometimes the head can become very noticeably flat. You can help prevent this by helping your baby get stronger and by changing his or head position regularly.

  • Make sure your baby gets "tummy time" every day. Place your baby on his or her tummy for playtime while you are watching closely. Let your baby "squirm" around, making sure that he or she can breathe easily. Tummy time helps your baby build strength and develop motor skills. These are important for helping your baby learn to move and hold his or her head up.
  • Cuddle your baby while holding his or her head up as much as you can. Don't place your baby in car seat carriers or bouncers for long periods each day. Holding your baby is better for all areas of development.
  • At least every week, change your baby's head position during sleep. (Remember to always keep your baby on his or her back during naps and at bedtime.) A good way to make sure your baby's head rests in different positions is to switch which end of the bed you place him or her each week. One week, place your baby so his or her feet are at the end of one end of the crib; the next week, place the feet at the other end. Babies usually turn their heads away from the wall, toward the inside of a room. If your baby's crib is not against a wall, you can try moving your baby's head position more to one side while he or she is sleeping.

Home Treatment

Dealing with grief

Losing a baby to SIDS is a tremendously painful experience. Each member of your family may respond in a different way. These different ways of coping with death can strain a marriage and a family. Along with grief, family members may be struggling with feelings of guilt. Support from family, friends, and possibly health professionals during this process is very important for everyone.

Click here to view an Actionset. Grief: Coping With Grief

Trusted doctors can help you after your baby's death. Be aware that your baby's death also can affect your doctor. He or she may recommend other trained professionals to give you the needed support. If you feel the response from your doctor is inadequate, seek help somewhere else. For instance:

  • Join a grief support group. Ask your doctor if one specifically for parents who have lost babies to SIDS is available in your area.
  • Visit a mental health professional (psychiatrist, psychologist, licensed professional counsellor). Many families benefit from group counselling to help them deal with the tensions that arise after the loss of a baby.
  • Talk with a close family member, friend, or clergy member.

For more information about and help with grief in general, see the topic Grief and Grieving.

Other Places To Get Help


Canadian Foundation for the Study of Infant Deaths (SIDS Foundation)
586 Eglinton Avenue East
Suite 308
Toronto, ON  M4P 1P2
Phone: (416) 488-3260
Fax: (416) 488-3864
Web Address:

Canadian Paediatric Society
2305 Saint Laurent Boulevard
Ottawa, ON  K1G 4J8
Phone: (613) 526-9397
Fax: (613) 526-3332
Web Address:

The Canadian Paediatric Society (CPS) promotes quality health care for Canadian children and establishes guidelines for paediatric care. The organization offers educational materials on a variety of topics, including information on immunizations, pregnancy, safety issues, and teen health.



  1. Community Paediatrics Committee, Canadian Paediatric Society (2004, reaffirmed 2010). Recommendations for safe sleeping environments for infants and children. Paediatrics and Child Health, 9(9): 659–663. Also available online:
  2. Public Health Agency of Canada (2010). Safe sleep for your baby. Available online:
  3. Hunt CE, Hauck FR (2007). Sudden infant death syndrome. In RM Kliegman et al., eds., Nelson Textbook of Pediatrics, 18th ed., pp. 1736–1742. Philadelphia: Saunders Elsevier.
  4. American Academy of Pediatrics (2005, reaffirmed 2008). Policy statement: The changing concept of sudden infant death syndrome: Diagnostic coding shifts, controversies regarding the sleeping environment, and new variables to consider in reducing risk. Pediatrics, 116(5): 1245–1255.
  5. Hauck F, et al. (2005). Do pacifiers reduce the risk of Sudden Infant Death Syndrome: A meta-analysis. Pediatrics, 116(5): 716–723.
  6. Sosinsky LS, Gilliam WS (2007). Child care. In RM Kliegman et al., eds., Nelson Textbook of Pediatrics, 18th ed., pp. 81–86. Philadelphia: Saunders Elsevier.

Other Works Consulted

  • Kerby GS, et al. (2009). Sudden infant death syndrome section of Respiratory tract and mediastinum. In WW Hay Jr et al., eds., Current Diagnosis and Treatment: Pediatrics, 19th ed., pp. 516–517. New York: McGraw-Hill.
  • Kinney HC, Thach BT (2009). The Sudden Infant Death Syndrome. New England Journal of Medicine, 361(8): 795–805.
  • Kline A, Gibson E (2006). Sudden infant death syndrome. In FD Burg et al., eds., Current Pediatric Therapy, 18th ed., pp. 258–260. Philadelphia: Saunders Elsevier.
  • Vennemann MM, et al. (2009). Does breastfeeding reduce the risk of Sudden Infant Death Syndrome? Pediatrics, 123(3): e406–e410.


By Healthwise Staff
Primary Medical Reviewer Susan C. Kim, MD - Pediatrics
Primary Medical Reviewer Andrew Swan, MD, CCFP, FCFP - Family Medicine
Specialist Medical Reviewer John Pope, MD - Pediatrics
Last Revised May 13, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.