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Sudden Infant Death Syndrome (SIDS)


Christopher P. Raab

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Feb 2023
Topic Resources

Sudden infant death syndrome is the sudden, unexpected death, usually during sleep, of a seemingly healthy infant between 1 month and 1 year of age.

  • The cause of sudden infant death syndrome (SIDS) is not known.

  • Putting infants to sleep on their back; removing pillows, bumper guards, and toys from the crib; protecting infants from overheating; and preventing infants from breathing second-hand cigarette smoke may help prevent SIDS.

  • Parents who have lost a child to SIDS should seek counseling and support groups.

There is more than one term used to describe a sudden infant death. Sudden unexpected infant death (SUID) is used broadly to describe any unexpected and sudden death in a child less than 1 year of age in which the cause is not obvious before an investigation is done. SUID includes sudden, unexpected deaths that have a cause, such as accidental deaths (resulting from accidental suffocation or strangulation), natural deaths (such as those resulting from an infection or a medical condition), and deaths due to intentional harm. SUID also includes sudden, unexpected deaths for which no cause is identified even after an evaluation or investigation is done, such as SIDS.

SIDS (also called crib death) is one of the most common causes of death in infants between 1 month and 1 year of age. It most often affects children between the second month and fourth month of life. The syndrome occurs worldwide. There are many risk factors.

There are racial and ethnic disparities. From 2015 to 2019, rates of SUID were highest in non-Hispanic American Indian/Alaska Natives, non-Hispanic Black people, and non-Hispanic Native Hawaiian/Other Pacific Islanders.

Risk factors for sudden infant death syndrome

Children who have or who are exposed to any of the following risk factors are at increased risk of SIDS:

Causes of SIDS

The cause of SIDS is unknown. It may be due to an abnormality in the control of breathing. Some infants with SIDS show signs of having had low levels of oxygen in their blood and having had periods when they stopped breathing (called apnea).

Laying infants down to sleep on their stomach and the use of soft bedding (such as pillows and lamb’s wool blankets) have been linked to SIDS. Sleeping together with an infant on a sofa, cushion, or bed (see Co-sleeping Co-sleeping Because the nervous system of newborns is immature, newborns sleep a great deal, but only for an hour or two at a time, regardless of whether it is day or night. By 4 to 6 weeks of age, many... read more ) also increases the risk of SIDS.

Did You Know...

  • Although rare, sudden infant death syndrome (SIDS) is one of the most common causes of death in infants between the ages of 1 month and 1 year. It is associated with laying infants down to sleep on their stomach.

Diagnosis of SIDS

Prevention of SIDS

  • Putting infants to sleep on their back

Despite the known risk factors for SIDS, there is no certain way to prevent it. However, certain measures seem to help, particularly putting infants to sleep on their back on a firm, flat sleep surface. The number of SIDS deaths has decreased dramatically as more parents have put their infants to sleep on their back for every sleep (see the Safe to Sleep® campaign).

Regular prenatal care during pregnancy may help lower the risk of SIDS.

There is no evidence that at-home breathing monitors reduce the risk of SIDS. There is also no evidence to recommend swaddling for prevention of SIDS.

Safe to Sleep: Reducing the Risk of Sudden Infant Death Syndrome

  • Position: Always place the infant on the infant’s back to sleep, for naps and at night. Stomach sleeping, side sleeping, and propping are unsafe.

  • Surface: Place the infant on a firm, flat sleep surface, such as a safety-approved crib mattress, covered by a fitted sheet. The surface should not be at an angle or on an incline.

  • Bedding: Keep soft objects, pillows, bumper guards, stuffed toys, stuffed animals, loose blankets, nonfitted sheets, mattress toppers, fur-like materials, quilts, comforters, and weighted blankets, swaddles, or objects out of the infant’s sleep area.

  • No smoking: Do not allow smoking or vaping around the infant. Smoking, nicotine, alcohol, marijuana, opioids, and illicit drug use should be avoided during pregnancy and after birth. Caregivers should be free of drugs and alcohol.

  • Location: Set up the infant’s sleep area close to but separate from the sleep area of the parents/caregivers and other children. It is recommended that infants sleep in the parents'/caregivers' room close to the parents'/caregivers' bed but on a separate surface designed for infants, ideally for at least the first 6 months.

  • Pacifiers: Consider giving the infant a clean, dry pacifier when placing the infant down for every sleep. For infants who are breastfeeding, wait to give a pacifier until breastfeeding is well established.

  • Temperature: Do not let the infant become too hot or too cold during sleep. Avoid overwrapping the infant or covering the head. Keep the infant warm with layers of clothing instead of with blankets and other coverings. Wearable blankets can also be used.

To help prevent flat spots from developing on the infant's head, infants should spend some time on their tummy when they are awake and someone is watching them (tummy time). Parents/caregivers can begin short periods of tummy time soon after hospital discharge. Tummy time should be increased regularly to at least 15 to 30 minutes a day by the time the infant is 7 weeks old.

To help make the infant's head round, parents/caregivers should change the direction that the infant lies in while in the crib each week and avoid leaving the infant for too long in car seats, carriers, and bouncers.

Home monitors and products that claim to prevent sudden infant death syndrome do not seem helpful.

Adapted from The National Institute of Child Health and Human Development's Safe Infant Sleep Basics: Ways to Reduce Baby’s Risk.

Resources for Parents Who Have Lost an Infant to SIDS

  • Counseling

  • Support groups

Most parents who have lost an infant to SIDS are grief-stricken and unprepared for the tragedy. They often feel guilty. The experience of the investigations conducted by police, social workers, or others may cause additional distress.

Counseling and support from specially trained doctors and nurses and other parents who have lost an infant to SIDS are critical to helping parents cope with the tragedy. Specialists can recommend reading materials, web sites (such as the American SIDS Institute), and support groups to assist parents.

More Information

The following English-language resources may be useful. Please note that THE MANUAL is not responsible for the content of these resources.

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