Frequently Asked Questions

What is SIDS?

Sudden Infant Death Syndrome (SIDS) is the sudden death of an infant under 1 year of age which remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and review of the clinical history (Willinger et al., 1991).

What are the most common characteristics of SIDS?

SIDS is unexpecterd, usually occurring in healthyappearing infants under 1 year of age. A SIDS death occurs quickly and usually during sleep. SIDS is rare during the first month of life. Although SIDS can occur in older infants, most SIDS deaths occur by the end of the sixth month, with the greatest number occurring in infants between 2 and 4 months of age (AAP, 2000).

In the United States, more SIDS cases are reported in the fall and winter than in spring or summer. SIDS occurs more often in boys than in girls (approximately a 60- to 40-percent male-to-female ratio). African-American and American-Indian infants are two to three times more likely to die from SIDS as other infants (AAP, 2000; NICHD, 2001). Several Government agencies are intensifying efforts to reach these populations with the latest information about SIDS.

How many babies die from SIDS?

Each year between 1983 and 1992, the average number of reported SIDS deaths ranged from 5,000 to 6,000. Over the past few years, especially since the mid 1990s, the number of SIDS deaths has declined significantly. The National Center for Health Statistics (NCHS) reported that in 2002 in the United States, 2,295 infants under 1 year of age died from SIDS (NCHS, 2004). Still, when considering the number of live births each year, SIDS remains the leading cause of death in the United States among infants between 1 month and 1 year of age and the third leading cause of death overall among infants less than 1 year of age (NCHS, 2004).

Although the overall SIDS rates have declined in all populations throughout the United States, disparities in SIDS rates and prevalence of risk factors remain in certain groups. SIDS rates are highest among African Americans and American Indians and are lowest among Asians and Hispanics (NICHD, 2001).

How is a SID death diagnosed?

By definition, a SIDS diagnosis requires a complete autopsy, a thorough death scene investigation, and a clinical history. A death is diagnosed as SIDS only after all probable alternatives have been eliminated—in other words, SIDS is a diagnosis of "exclusion."

Often, the cause of an infant death can be determined only through a process of collecting information; conducting sometimes complex forensic tests; and by talking with parents, other caregivers, and physicians.

Medical and legal experts rely on three methods to determine a SIDS death.  Read more here »

What is the best way to reduce my baby’s risk for SIDS?

Placing your baby on his or her back to sleep for every sleep time is the best way to reduce the risk of SIDS.
Learn more about how to reduce the risk for SIDS on the risk reduction page.

Will my baby choke if placed on the back to sleep?

No. Healthy babies naturally swallow or cough up fluids—it’s a reflex all people have. Babies might actually clear such fluids better when on their backs.

What if my baby rolls onto the stomach on his or her own during sleep? Do I need to put my baby in the back sleep position again if this happens?

No. Rolling over is an important and natural part of your baby’s growth. Most babies start rolling over on their own around 4 to 6 months of age. If your baby rolls over on his or her own during sleep, you do not need to turn the baby over onto his or her back. The important thing is that the baby start off every sleep time on his or her back to reduce the risk of SIDS, and that there is no soft, loose bedding in the baby’s sleep area.

What are the risk factors?

Although sleep position, smoke exposure, overheating, and infant bedding have been identified as risk factors for SIDS, researchers have identified a number of other factors that may put an infant at increased risk for SIDS.

Infant Care Practices and SIDS Risk Reduction

Several studies have examined various environmental influences or child-rearing practices that may help protect an infant from SIDS (Valdes-Dapena, 1995; Hoffman et al., 1996; NICHD, 2000). It is important to point out, however, that these factors, in and of themselves, are not reliable in predicting how, when, why, or if SIDS will occur.

For example, although researchers conclude that breastfeeding is beneficial, there is no clear-cut link between breastfeeding and reduced risk of SIDS. Other studies have found a lower rate of SIDS among infants who used pacifiers compared with infants who did not use pacifiers. Although results of these studies tend to be consistent, there is still no evidence that pacifier use prevents SIDS(AAP, 2000).

Maternal Risk Factors

Still other risk factors, called maternal risk factors, are associated with how the mother's behavior and health affect the infant before and after birth.

Maternal risk factors include:

  • age less than 20 at first pregnancy
  • a short interval between pregnancies
  • late or no prenatal care
  • smoking during and/or after pregnancy
  • placental abnormalities
  • low weight gain during pregnancy
  • anemia
  • alcohol and substance abuse
  • history of sexually transmitted disease or urinary tract infection

What do current research findings and theories indicate?

Most scientists now believe that babies who die of SIDS are born with one or more conditions that make them especially vulnerable to the internal and external stresses that occur in the life of any infant. Currently, many researchers argue that the clue to finding the cause(s) of SIDS lies in a further understanding of the development and functions of the brain and nervous system of SIDS infants.

These scientists theorize that some babies at risk for SIDS have defects in those parts of the nervous system that control breathing and heart rate. Maturation of the brainstem may be delayed in SIDS infants. Myelin, a fatty substance that facilitates nerve signal transmission, appears to develop more slowly in SIDS infants than in other babies.

"The detection of subtle abnormalities in SIDS brains indicates that not all SIDS infants are 'normal' despite their lack of clinical abnormalities. The occurrence of brain abnormalities supports the concept that a vulnerable, and not a normal, infant is at risk for SIDS. The idea of a vulnerable infant forms a key part of a triple-risk model for the pathogenesis of SIDS" (Filiano and Kinney, 1994).

Read more about the Triple Risk Model here »

Brain Abnormalities in SIDS Infants

A team of researchers funded by the National Institute of Child Health and Human Development (NICHD) has discovered that infants who die of SIDS may have abnormalities in several parts of the brainstem. This finding builds on the results of an earlier study that identified abnormalities in the region of the brain known as the arcuate nucleus in babies who died of SIDS.

In the NICHD study, SIDS infants were found to have decreased binding of serotonin in the nucleus raphe obscurus, a brain structure linked to the arcuate nucleus, as well as four other brain regions. These areas of the brain are thought to play a crucial role in regulating breathing, heart beat, body temperature, and arousal (Panigrahy et al., 2000).

What is the Back to Sleep campaign?

Since its inception in 1994, the Back to Sleep campaign has focused on heightening awareness among parents, health care providers, and other caregivers about the benefits of putting a baby to sleep on his or her back. Over the course of the campaign, almost 80 million brochures, posters, public service announcements, and informational videos have been distributed. The Back to Sleep campaign continues as a nationwide public health effort, with NICHD having major responsibility for disseminating information and educational materials on this crucial health topic.

Back in 1994 when the Back to Sleep campaign was first initiated, there were almost twice as many SIDS deaths among African-American infants than among White infants. Despite the almost 50 percent drop in the number of SIDS deaths in both groups, a significant disparity still exists (NICHD, 2002). To continue efforts to reach minority and hard-to-reach populations about the importance of placing an infant on its back to sleep, NICHD has partnered with community groups to provide outreach to minority and underserved communities.

About SIDS deaths in child care settings?

Twenty percent of SIDS deaths occur in a day care setting (Moon, Patel, and Shaefer, 2000). Although media and mailings have been largely effective in communicating BTS information to many child care centers, nonprone positioning and other risk reduction measures are not universally practiced among child care providers (Moon and Biliter, 2000). To promote these messages in child care settings, the Health Resources and Services Administration's Maternal and Child Health Bureau is sponsoring the Healthy Child Care America Back to Sleep campaign. The campaign, which was officially launched in January 2003, is a nationwide effort to unite child care, health, and SIDS prevention partners to reduce the risk of deaths in child care settings (AAP, 2003).

Over the past 9 years, the Back to Sleep campaign has been extremely effective in helping reduce the number of SIDS deaths. AAP cautions, however, that while continuing to emphasize the "importance of infant positioning for sleep as an effective modifiable risk factor for SIDS," it is also important to "focus increased attention on other modifiable environmental factors, to describe complications that may have arisen from modifying risk factors, and to make recommendations about other strategies that may be effective for further reducing the risk of SIDS" (AAP, 2000).