Merck Manual

Please confirm that you are not located inside the Russian Federation

honeypot link
Quick Facts

Sudden Infant Death Syndrome (SIDS)


The Manual's Editorial Staff

Last full review/revision Dec 2019| Content last modified Dec 2019
Click here for the Professional Version
Get the full details

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 (

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version


Others also read

Test your knowledge

Diabetic Ketoacidosis
Diabetic ketoacidosis is a complication of diabetes. It occurs mostly in people with type 1 diabetes. Diabetic ketoacidosis occurs when a lack of insulin prevents glucose in the bloodstream from entering the cells. Without adequate glucose, the cells burn fat for energy, producing compounds called ketones. Ketones supply some energy, but they also make the blood too acidic. There are several causes of ketoacidosis. Which of the following is a cause of ketoacidosis?
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID

Also of Interest

Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID
Download the Manuals App iOS ANDROID