SIDS (Sudden Infant Death Syndrome)

SIDS stands for sudden infant death syndrome. SIDS is the sudden and unexplained death of an infant between the ages of 1 month and 1 year old that doesn’t have a known cause, even after a complete investigation. The exact cause of SIDS is unknown, but there are known risk factors and ways to reduce your baby’s chances of dying from the condition.


What is SIDS?

Sudden infant death syndrome (SIDS) is the term used to describe the sudden and unexplained death of an infant who’s between 1 month and 1 year of age, even after thorough investigation. This investigation includes performing an autopsy, examining the death scene and reviewing the baby’s medical history. If the medical examiner or coroner can’t find a cause for the death and the infant was younger than 1 year old, they’ll call the death SIDS.

Most babies who die of SIDS are between 2 and 4 months old, and 90% are younger than 6 months old. Most of these babies appear to have died during their sleep, usually between the hours of midnight and 6 a.m. This is why other names for SIDS include “crib death” or “cot death.” Cribs don’t cause SIDS, but a baby’s sleep environment can affect sleep-related causes of death. The best way to prevent SIDS is by placing your baby to sleep on their back.


SIDS isn’t the cause of every sudden infant death. Every year, thousands of infants in the U.S. die suddenly and unexpectedly. Researchers call these deaths SUID, which stands for sudden unexpected infant death. SUID includes all unexpected deaths. It includes those with a clear cause, such as suffocation, and those without a known cause, such as SIDS. One-half of all SUID cases are SIDS.

How common is SIDS?

SIDS is the leading cause of death in babies between 1 month and 1 year old in the United States. About 2,500 infants die every year because of SIDS.


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Symptoms and Causes

Risk factors for SIDS include teen pregnancy, alcohol or tobacco use during pregnancy, premature birth and low birth weight.
SIDS doesn’t have a clear cause but there are risk factors that may lead to the unexplained deaths.

What are the symptoms of SIDS?

Almost all deaths that occur due to SIDS happen without any warning signs or symptoms.

What causes SIDS?

Sudden infant death syndrome is, by definition, an unexplained death, so the cause of SIDS is unknown. However, researchers have studied potential SIDS causes to try to better understand how it occurs. The most commonly agreed-upon theory is that babies who die of SIDS have an underlying vulnerability, such as a genetic pattern or a brain abnormality. Then, when they’re exposed to a trigger during early brain or immune system development, that vulnerability causes sudden death. Risk factors for SIDS and this predisposition include:

Researchers believe infants who die of SIDS have issues with the way they respond to these triggers and how they regulate their breathing, heart rate and temperature.

Do vaccines cause SIDS?

Vaccines don’t cause SIDS. There’s no scientific evidence that childhood vaccinations increase the likelihood of SIDS. Although there are reports of babies dying shortly after vaccination, this is because most babies in the age range at risk for SIDS are receiving routine vaccines.

In addition, the number of SIDS cases has fallen by more than 50% since the mid-1980s, yet the number of vaccines providers have given since that time has continued to rise. In fact, recent research has shown that vaccines may actually have a protective effect against SIDS.

Other things that don’t cause SIDS include:

  • Cribs.
  • Choking or vomiting.
  • Child abuse or neglect.
  • Infections and illnesses.

Is SIDS contagious?

No. An infection doesn’t cause SIDS, so it can’t be spread or caught.



How can I prevent SIDS?

Preventing SIDS isn’t always possible, but there are things you can do to reduce your baby’s risk. SIDS prevention starts with keeping your baby’s sleep space safe:

  • Don’t share a bed with your baby if you or your baby has any of the above risk factors.
  • Have your baby sleep in your room with you but on a separate sleeping surface for at least six months. Examples include a sidecar attached to the bed or a bassinet to make breastfeeding easier, or, if you’re not breastfeeding, a portable or permanent crib. Sharing your bedroom with your baby can reduce their risk of SIDS by up to 50%.
  • Use a new, baby-friendly crib that has a design meant to keep your baby from falling between the side of the crib and the mattress. Make sure your baby’s head can’t get caught or trapped between the bars of the crib. Opt for a firm crib mattress over a soft one. Make sure the mattress is flat and level.
  • Remove all loose bedding from your baby’s sleeping environment. This includes all blankets, pillows, stuffed animals, toys and crib bumpers. Your baby can choke on these items and stop breathing, or the items can strangle your baby. A fitted sheet should be the only thing on your baby’s mattress.
  • Place your baby down on their back — not on their side or their tummy — for naps and bedtime. Your baby’s muscles aren’t yet fully developed and they can’t lift their head. If your baby is laying on their stomach, they can’t lift their head to breathe.
  • Keep your bedroom cool. Research has shown when babies get overheated they may fall into a deeper sleep, making it more difficult to wake them up when their bodies are telling them to breathe.
  • Avoid swaddling once your baby can roll over.

Other ways to prevent SIDS include:

  • Get your baby vaccinated: Research suggests that getting your baby’s vaccines on time reduces their risk of SIDS by up to 50%.
  • Breastfeed (chestfeed): Research has shown that breastfeeding your baby lowers their risk for SIDS.
  • Offer your baby a pacifier: Scientists believe pacifiers may allow your baby’s airway to open more or may prevent your baby from falling into a deeper sleep, reducing the threat of SIDS.
  • Avoid beverages containing alcohol and tobacco products: Don’t use alcohol or tobacco products during and after your pregnancy.
  • Don’t use breathing monitors: Researchers haven’t found products marketed to reduce or prevent SIDS, such as breathing monitors, to be effective.
  • Tummy time: Give your baby plenty of “tummy time” when they’re awake and you or another caregiver is supervising them. This will also help prevent plagiocephaly (flat head syndrome).

Living With

When should my baby see their healthcare provider?

While there’s no way to completely prevent SIDS, one thing you can do to lower your baby’s risk is to make sure they see their healthcare provider for all of their routine well-baby care visits. At these appointments, your baby’s provider will make sure your baby is healthy and developing as expected. Your baby will receive all of their recommended vaccinations. And you’ll have the opportunity to ask any questions you have about keeping your baby safe.


Additional Common Questions

What does SIDS stand for?

SIDS stands for sudden infant death syndrome.

When is SIDS most common?

SIDS is most common between the ages of 2 and 4 months, with 90% of SIDS deaths occurring before the age of 6 months.

How many babies die from SIDS?

About 2,500 babies in the United States die every year due to SIDS. While this SIDS statistic may sound alarming, the condition is rare and your baby’s risk of dying from it is very low.

A note from Cleveland Clinic

Losing a baby to SIDs can be overwhelming. You may be feeling anger, sadness, guilt or shock. All feelings are valid. If SIDS has affected you, it’s important to reach out for help and support. Your healthcare provider can help you find resources to guide you through the grieving process. You may find it helpful to join a support group for parents or caregivers who have lost a baby to SIDS. Or you may prefer to talk to a counselor one-on-one. Either way, give yourself time to heal as you cope with this unimaginable loss.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 05/22/2023.

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