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Quick Facts

Sudden Infant Death Syndrome (SIDS)


The Manual's Editorial Staff

Last full review/revision Dec 2019| Content last modified Dec 2019
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What is SIDS?

Sudden infant death syndrome (SIDS) is the unexpected death of a baby who previously seemed healthy. The death occurs during sleep for no clear reason. That's why it’s sometimes called crib death.

  • SIDS most often happens in babies 2 to 4 months old but can occur up to 1 year

  • Doctors don’t know what causes SIDS but think it might be related to how babies' brains control breathing

  • Putting babies to sleep on their back and keeping pillows and bumpers out of the crib may help prevent SIDS

  • It's common for parents and caregivers to feel shock, grief, and guilt—doctors may suggest counseling and support groups by people who are trained to help these parents cope

What causes SIDS?

Doctors don't know for sure what causes SIDS. It probably involves problems with the parts of the brain that control breathing and heartbeat.

However, certain babies are more likely to have SIDS, including those who:

  • Sleep on their stomach (biggest single risk)

  • Sleep in their parents' bed

  • Sleep in very soft bedding

  • Are boys, black, and/or Native American

  • Have mothers who are single, under age 20, or have smoked cigarettes or used street drugs during pregnancy

  • Have a low-income family

  • Have a brother or sister who died of SIDS

How can I prevent SIDS?

To lower the risk of SIDS:

  • Place your baby on his or her back for naps and night sleeping

  • Use a firm mattress in your baby's crib—don't sleep with your baby on a sofa or in your bed

  • Keep soft objects, like toys, blankets, pillows, and loose bedding, away from your sleeping baby

  • Keep your baby away from cigarette smoke

  • Have your baby sleep in an area separate from you, but nearby

  • If your baby uses a pacifier, offer a clean, dry one at bedtime

  • Make sure your baby isn't too hot while sleeping

Don't depend on a baby monitor to help prevent SIDS.

Where can I get more information about SIDS?

American SIDS Institute (

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