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:
Sleeping on the stomach (most important risk factor)
Brother or sister died of SIDS
Cold temperatures/winter months
Growth failure
Insufficient or no prenatal care
Low birth weight
Low-income family
Male sex
Mother has had many pregnancies
Mother under age 20
Mother smoked, drank alcohol, or used drugs during pregnancy
Non-Hispanic American Indian/Alaska Natives, non-Hispanic Black people, and non-Hispanic Native Hawaiian/Other Pacific Islanders race or ethnicity
No pacifier
Old or unsafe crib
Overheating (caused by blankets or a hot room)
Pauses in breathing (apnea) that required resuscitation
Recent illness
Sharing a bed with a parent or caretaker (bed-sharing or 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 )
Short amount of time between pregnancies
Single mother
Smoking in the home
Soft bedding
Upper respiratory tract infection
Waterbed mattress
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.
Diagnosis of SIDS
Autopsy
Doctors cannot make the diagnosis of SIDS without an autopsy (an inspection and examination of a body after death) to rule out other causes of sudden, unexpected death (such as intracranial hemorrhage Bleeding in and around the brain Birth injury is damage that occurs as a result of physical pressure during the birthing process, usually during transit through the birth canal. Many newborns have minor injuries during birth... read more 
, meningitis Meningitis in Children Bacterial meningitis is a serious infection of the layers of tissue covering the brain and spinal cord ( meninges). Bacterial meningitis in older infants and children usually results from bacteria... read more , or myocarditis Myocarditis Myocarditis is inflammation of the muscle tissue of the heart (myocardium) that causes tissue death. Myocarditis may be caused by many disorders, including infection, toxins and drugs that affect... read more ).
Doctors also need to assess whether the infant suffocated or died as the result of abuse.
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.
Breastfeeding Breastfeeding Breast milk is the ideal food for newborns and infants. Although babies may be fed breast milk or formula, the World Health Organization (WHO) and American Academy of Pediatrics (AAP) recommend... read more 
and preventing infants from breathing second-hand smoke may help and clearly have other health benefits.
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.
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.
National Institute of Child Health and Human Development (NICHD): Safe to Sleep®: Information for parents and caregivers about safe sleep practices for infants
NICHD: Safe Infant Sleep Basics: Ways to Reduce Baby’s Risk: Recommendations for parents and caregivers about the most effective ways to reduce the risk of SIDS
American SIDS Institute: An organization providing education about causes of and ways to prevent SIDS and family support services
