What are the Risk Factors of SIDS?
Currently there is no known way to prevent SIDS, but there are things that parents and caregivers can do to reduce the risk of a SIDS death. For example, researchers now know that the mother's health and behavior during her pregnancy and the baby's health before birth seem to influence the occurrence of SIDS.
Scientists also know that certain environmental and behavioral influences (called risk factors) can make an individual more susceptible to disease or ill health. Although risk factors are not necessarily the cause of a condition, by studying risk factors, scientists are able to better understand a disease or condition, which often leads to detecting a cause.
SIDS researchers and clinicians continue to try to identify risk factors that can be modified or controlled to reduce an infant's risk for SIDS. For example, SIDS experts now know that the baby's sleep position, exposure to smoke, and becoming overheated while asleep can increase the infant's risk for SIDS.
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Infant Sleep Position
In April 1992, the American Academy of Pediatrics (AAP) Task Force on Infant Sleep Position issued a statement recommending that infants be placed on their backs to sleep to reduce the risk of SIDS. Then, in 1994, the U.S. Public Health Service, AAP, the SIDS Alliance, and the Association of SIDS and Infant Mortality Programs cosponsored the Back to Sleep campaign, a national public service initiative to disseminate AAP's recommendation that infants be placed on their back to sleep.
Between 1992 and 1998, among U.S. infants, stomach (prone) sleeping decreased more than 70 percent to approximately 20 percent. During that same time frame, the number of SIDS deaths declined by more than 40 percent (Willinger et al., 1998; AAP, 200; NICHD, 2001). Not surprisingly, most researchers, policymakers, and SIDS professionals agree this significant decline occurred largely as a result of changing sleep position (AAP, 2000).
Rates of SIDS are over twice as high among American Indians and African-Americans compared with Whites. Prone sleeping was found to be a significant risk factor for SIDS in an African-American urban sample (Hauck et al., 2002). These authors recommend educational outreach to the African-American community.
Another recent study of the relationship between infant sleep position and SIDS concluded that infants placed in an unaccustomed prone or side sleeping position are at a higher risk of SIDS (Li et al., 2003). This ethnically diverse, population-based, case-controlled study was conducted in 11 counties in California. The health message from this research is that babies should be on their backs for all sleep, including naps.
Exposure to Smoke
Researchers have concluded that if a mother smokes during or after pregnancy, she is placing her infant at a greater risk for SIDS (AAP, 2000). Some studies suggest that exposure of the newborn to tobacco smoke (whether or not the mother smokes) may be associated with an increased risk for SIDS. In a 1997 policy statement, AAP cautioned, "Exposure of children to environmental tobacco smoke is associated with increased rates of lower respiratory illness and increased rates of middle ear effusion, asthma, and SIDS" (AAP, 1997).
Overheating
According to AAP (2000), some evidence points to an association of the amount of clothing or blankets on an infant, room temperature, and the time of the year with an increased risk for SIDS. The increased risk associated with overheating is particularly clear when infants are placed on their stomachs (prone).
AAP cautions that the possible relationship between clothing and climate as stand-alone factors (or as a cluster of environmental risk factors) is less clear. Moreover, although the number of recorded SIDS deaths has been higher in the winter months, that increase may be due to the greater frequency of colds, flu, and other infections during the winter.
Infant Bedding
Researchers and consumer safety advocates continue to look for a possible link between SIDS and soft bedding (Scheers, Dayton, and Kemp, 1998). During 2000, seven major retailers joined with the U.S. Consumer Product Safety Commission (CPSC) to kick off a nationwide campaign promoting safe bedding practices for infants. Many retailers are developing public service campaigns to spread this message to parents and other caregivers. The hope is that by circulating this information, infant deaths will be reduced and that those responsible for infant care will receive one consistent message about ensuring a safe sleeping environment for babies.
In recent safety alerts, CPSC has warned parents to guard against unfounded claims from manufacturers of some infant bedding materials that the use of certain products can reduce SIDS. Parents and other caregivers need to be aware that there is no product currently available that can guarantee prevention of a SIDS death.
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Other 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 an 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 (Valde-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 did not use pacifiers. Although results of these studies tend to be consistent, there is still no evidence that pacifier use increases the risk of SIDS (AAP, 2000).
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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:
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- age less than 20 at first pregnancy
- 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 (NICHD, 2001).
AAP Revises SIDS Risk Reduction Recommendations
“The Changing Concept of Sudden Infant Death Syndrome: Diagnostic Coding Shifts, Controversies Regarding the Sleep Environment, and New Variables to Consider in Reducing Risk”
released October 10, 2005 by John Kattwinkel, MD
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Despite major decreases in the incidence of Sudden Infant Death Syndrome (SIDS) over the past decade, SIDS is still responsible for more infant deaths beyond the newborn period in the United States than any other cause of death during infancy. In an updated policy statement on "The Changing Concept of Sudden Infant Death Syndrome: Diagnostic Coding Shifts, Controversies Regarding the Sleeping Environment, and New Variables to Consider in Reducing Risk," the American Academy of Pediatrics (AAP) addresses several issues that have become relevant since they last published a statement in 2000.
The AAP no longer recognizes side sleeping as a reasonable alternative to fully supine (lying on back) sleeping. Studies have found that the side sleep position is unstable and increases the chances of the infant rolling onto his or her stomach. Every caregiver should use the back sleep position during every sleep period.
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Bed sharing is not recommended during sleep. Infants may be brought into bed for nursing or comforting, but should be returned to their own crib or bassinet when the parent is ready to return to sleep. However, there is growing evidence that room sharing (infant sleeping in a crib in parent's bedroom) is associated with a reduced risk of SIDS. The AAP recommends a separate but proximate sleeping environment.
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Research now indicates an association between pacifier use and a reduced risk of SIDS, which is why the revised statement recommends the use of pacifiers at nap time and bedtime throughout the first year of life. The evidence that pacifier use inhibits breastfeeding or causes later dental complications is not compelling enough to discredit the recommendation. However, it is recommended that pacifier introduction for breastfed infants be delayed until one month of age to ensure that breastfeeding is firmly established. In addition, if the infant refuses the pacifier, it should not be forced. There is a slight increased risk of ear infections associated with pacifier use, but the incidence of ear infection is generally lower in the first year of life, especially the first six months, when the risk of SIDS is the highest.
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The following have been consistently identified as risk factors for SIDS: prone (lying on stomach) sleep position, sleeping on a soft surface, maternal smoking during pregnancy, overheating, late or no prenatal care, young maternal age, preterm birth and/or low birth weight and male gender. Consistently higher rates of SIDS are found in black and American Indian/Alaska Native children - two to three times the national average.
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The policy recommendations include:
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* Back to sleep: Infants should be placed for sleep in a supine (wholly on back position) for every sleep.
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* Use a firm sleep surface: A firm crib mattress, covered by a sheet, is the recommended sleeping surface.
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* Keep soft objects and loose bedding out of the crib: Pillows, quilts, comforters, sheepskins, stuffed toys and other soft objects should be kept out of an infant's sleeping environment.
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* Do not smoke during pregnancy: Also avoiding an infant's exposure to second-hand smoke is advisable for numerous reasons in addition to SIDS risk.
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* A separate but proximate sleeping environment is recommended such as a separate crib in the parent's bedroom. Bed sharing during sleep is not recommended.
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* Consider offering a pacifier at nap time and bedtime: The pacifier should be used when placing infant down for sleep and not be reinserted once the infant falls asleep.
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* Avoid overheating: The infant should be lightly clothed for sleep, and the bedroom temperature should be kept comfortable for a lightly clothed adult.
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* Avoid commercial devices marketed to reduce the risk of SIDS: Although various devices have been developed to maintain sleep position or reduce the risk of rebreathing, none have been tested sufficiently to show efficacy or safety.
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* Do not use home monitors as a strategy to reduce the risk of SIDS: There is no evidence that use of such home monitors decreases the risk of SIDS.
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* Avoid development of positional plagiocephaly (flat back of head): Encourage "tummy time."
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* Avoid having the infant spend excessive time in car-seat carriers and "bouncers." Place the infant to sleep with the head to one side for a week and then changing to the other.
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* Assure that others caring for the infant (child care provider, relative, friend, babysitter) are aware of these recommendations.
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