US Pharm. 2013;38(5):HS14-HS16.

ABSTRACT: Sudden infant death syndrome (SIDS) is the sudden death of a baby that remains unexplained after a thorough investigation. SIDS is thought to occur when an infant with a predisposition to SIDS experiences stress from an exogenous source, such as asphyxia during sleep. Several factors have been found to increase the risk of SIDS, including the prone sleeping position. The number of SIDS cases decreased dramatically when it was recommended that infants be placed on their backs to sleep, but the incidence has plateaued. Regardless of practice site or specialty, all pharmacists can provide education on SIDS risk-reduction strategies in an effort to keep infants safe.

The current definition of sudden infant death syndrome (SIDS) is the sudden death of a baby aged younger than 1 year that remains unexplained after a thorough investigation, including scene investigation, autopsy, and a review of clinical history.1 SIDS is the leading cause of death among healthy infants in the United States.2 The incidence of SIDS underwent a dramatic decrease between 1994 and 2001; since that time, however, it has reached a plateau, and SIDS continues to be a significant cause of infant mortality.

SIDS History

SIDS was first defined in 1969 at a National Institutes of Health (NIH) consensus conference as the “sudden death of an infant or young child, which is unexpected by history, and in which a thorough postmortem examination fails to demonstrate an adequate cause of death.”3 The incidence of SIDS peaked at age 2 to 4 months, with a male predominance, and autopsy results demonstrated the presence of intrathoracic petechiae. The definition has changed over time and is now limited to infants aged less than 12 months, with death occurring during sleep.4

In the 1970s and 1980s, the incidence of SIDS appeared to increase in many developed countries and was especially high in New Zealand.5 Researchers around the world conducted epidemiological studies to identify risk factors for SIDS. In 1990, a case-control study in the United Kingdom found an estimated 8.8 times greater risk of SIDS in infants in the prone (face-down) sleeping position.6 In 1991, the New Zealand Cot Death Study Group estimated a 3.53 times greater risk of SIDS in prone infants.7

Because of these striking data, the NIH, in conjunction with the American Academy of Pediatrics (AAP) and other groups, organized the Back to Sleep campaign in the early 1990s. As a result, the incidence of SIDS decreased by 50% to 70%.8 However, since 2001, the incidence has plateaued, and SIDS currently remains a significant cause of infant mortality in the U.S. and worldwide.

Pathophysiology and Risk Factors

The term sudden and unexpected infant death (SUID) describes all deaths that are sudden and unforeseen in the infant age group, regardless of cause. When the death occurs during sleep and no known cause is revealed by complete autopsy, death-scene investigation, review of the circumstances of death, and clinical history, the case is officially defined as SIDS. SIDS encompasses approximately 80% of SUID cases.4 Since SIDS was initially described, several theories regarding pathophysiology have been proposed and subsequently dismissed.

The leading theory supported by the literature is the triple-risk model, first described in 1994.9 This model suggests that SIDS is the result of three simultaneous factors. First, the infant must have an underlying vulnerability that predisposes him or her to SIDS. There also must be stress from an exogenous source, such as asphyxia associated with a prone sleeping position. Finally, this stress must occur during a critical period of development (first 12 months of life). It is difficult to identify the underlying vulnerabilities, and current research is focusing on this problem.

Thus far, two disease states have been identified that may predispose some infants to sudden death. Considerable data link inherited disorders of fatty acid oxidation—most commonly, mutations in the medium-chain acyl-coenzyme A dehydrogenase gene—to unexpected infant death, accounting for approximately 1% of SUID cases.10 Genetic cardiac channelopathies are responsible for 5% to 10% of SUID cases.11,12 Other factors associated with increased SIDS incidence are bed-sharing in adult beds, sleeping on couches and armchairs, overheating, exposure to tobacco smoke, head or face covered with clothing or blankets, and the prone sleeping position. Some factors seem to have a protective effect, such as breastfeeding, pacifiers, and regular immunizations.

Current topics of research include autonomic nervous system disturbances and the effect of nicotine on the developing brain.1 Defects in normal arousal mechanisms are suspected to contribute to SIDS.13 The association between the prone sleeping position and SIDS is believed to be due to increased likelihood of rebreathing exhaled air, upper-airway obstruction, and hyperthermia in the face-down position. Also, infants may not yet have learned appropriate head-lifting and head-turning in response to asphyxia, or may have a deficit in neuronal pathways and reflexes that results in inefficient arousal and protection from the exogenous stressor.4

AAP Recommendations for Prevention

In 2011, the AAP released a policy statement detailing recommendations for a safe infant sleeping environment.14 These recommendations were developed to reduce the risk not only of SIDS, but of all sleep-related deaths in infants aged up to 12 months, such as suffocation, asphyxia, and entrapment. Depending upon individual medical conditions, a physician may recommend otherwise after considering the risks and benefits.14

Sleep Position: Based on data linking the prone sleeping position to an increased risk of SIDS, the AAP recommends that all infants aged less than 1 year be placed in the supine position (on their backs). Side sleeping, which was determined to be unsafe, is not recommended. Even infants with gastroesophageal reflux should be placed in the supine position, with rare exceptions for those who also have impaired airway-protective mechanisms.15 It is unsafe to elevate the head of the crib while the infant is supine, because he or she could slide into a position that compromises respiration.16 Once the infant can roll from supine to prone and from prone to supine, he or she may be allowed to remain in the position thus assumed.

Sleeping Environment: Infants should sleep on a firm surface, specifically a firm crib mattress covered by a fitted sheet. The AAP recommends using a crib, bassinet, or portable crib or play yard that conforms to the safety standards of the U.S. Consumer Product Safety Commission and ASTM International.14 Only mattresses designed for the specific crib should be used, and to prevent entrapment, there should be no gaps between the mattress and the side of the crib. If a mattress cover is used, it should be tightly fitting and thin. Infants should not sleep on beds, as there is a risk of entrapment and suffocation. Similarly, portable bed rails should not be used because they can cause entrapment and strangulation. Car seats, strollers, swings, infant carriers, and slings are not recommended for routine sleep because the infant may assume a position that causes airway obstruction.

Room-sharing without bed-sharing is recommended. This sleeping arrangement can reduce SIDS risk by as much as 50% and will likely prevent the suffocation, strangulation, and entrapment that could occur in an adult bed.14 The infant should sleep in his or her own crib, which should be placed close to the parents’ bed. The infant may be brought into the bed for feeding or comforting, but must be placed back in the crib when the parent is ready to sleep. Infants should not be fed on couches or armchairs when the parent is very tired, because of the extremely high risk of SIDS and suffocation associated with these circumstances. Some devices intended to make bed-sharing safer, such as cosleepers, have been developed, but they are not considered safe and are not recommended.

Soft objects and loose bedding must be kept out of the crib to reduce the risk of SIDS or SUID. Blankets and sheets may be hazardous and should not be used in the crib of an infant younger than 12 months.17,18 Bumper pads also should not be used; they have not been demonstrated to prevent injury and are a potential danger.

Prenatal and Postnatal Considerations: There are many reasons that it is important for pregnant women to receive appropriate and regular prenatal care. Epidemiological data suggest a substantial decrease in SIDS risk in infants whose mothers received proper prenatal care. Pregnant women should avoid exposure to smoke, alcohol, and illicit drugs because of the detrimental effects on the unborn child. Even secondhand tobacco smoke is injurious to the fetus.19

After the infant is born, avoidance of smoke exposure remains extremely important. Smoke exposure has been consistently identified as a risk factor for SIDS, with an especially high risk when an infant shares a bed with an adult smoker.19 Postnatal exposure to alcohol and illicit drugs also increases SIDS risk, particularly if the infant shares a bed with the parent who is using the substance.20

Breastfeeding is recommended by the AAP for many reasons, including a decreased risk of SIDS. If possible, mothers should breastfeed exclusively for 6 months.21 If this is not possible, any amount of breastfeeding is more protective than no breastfeeding at all.21

Pacifier Use: Parents and caregivers should consider offering a pacifier at bedtime and naptime. Although the mechanism of protection is not completely understood, studies have reported a decline in SIDS incidence with the use of pacifiers.22 Interestingly, the protective effect persists throughout the sleep period, even if the pacifier falls out of the infant’s mouth. Finger-sucking has not shown the same benefit. If the infant refuses the pacifier, the parent should not force it, but rather try again when the infant is a little older. The pacifier should not be hung around the infant’s neck, as this practice poses the risk of strangulation; similarly, objects such as stuffed toys should not be attached to the pacifier, since they present a choking hazard. In breastfed infants, pacifier use should be delayed until breastfeeding has been established, usually at age 3 to 4 weeks.21

Overheating: Many studies have identified overheating as a risk factor for SIDS.23 However, because these studies defined “overheating” variously, there is no specific recommendation for a safe room temperature. The AAP recommends that infants be dressed appropriately for the environment and that they wear no more than one layer beyond what an adult would wear to be comfortable in that environment. Parents and caregivers should monitor an infant for overheating by checking for sweating or a chest that feels hot to the touch. Overbundling and covering the face and head must be avoided.24

Immunizations: Infants should be immunized in accordance with AAP and CDC recommendations (updated annually). Immunizations have not been found to increase the risk of SIDS; in fact, they may have a protective effect.25,26

Preventive Devices: Some devices purported to reduce the risk of SIDS have been marketed, including wedges, positioners, special mattresses, and special sleep surfaces. There is no evidence that these devices reduce the risk of SIDS or suffocation, or that they are even safe.14 Therefore, manufacturers should not claim that a product protects against SIDS unless there is scientific evidence to support the claim. There also is no evidence supporting the use of home cardiorespiratory monitors as a risk-reduction strategy. These monitors may be useful in selected infants to detect apnea and bradycardia, but should not be used routinely.

Tummy Time: For several reasons, the AAP recommends supervised “tummy time” while the infant is awake.14 First, tummy time facilitates the infant’s development by strengthening neck and upper-body muscles and allowing the infant to practice lifting and turning his or her head. Additionally, tummy time will minimize positional plagiocephaly (flattened back of the head caused by spending excessive time in the supine position). To further prevent this deformity, infants should not spend excessive time in car seats.

Provider and Research Recommendations: The AAP policy statement includes recommendations for health care professionals and researchers. Staff should endorse the SIDS risk-reduction recommendations from birth, including in the neonatal ICU (NICU) once the infant is stable, and well in advance of discharge.14 Additionally, pediatricians should actively undertake to educate parents and caregivers about these recommendations. Continued investigation of the risk factors, causes, and pathophysiological mechanisms of SIDS and other sleep-related infant deaths is encouraged.14

Conclusion

SIDS remains a significant cause of infant mortality despite the drastic decrease in incidence in the 1990s and early 2000s. Although SIDS is not highly medication related, pharmacists can play a critical role. Community pharmacists, in particular, have the opportunity to reach a large number of parents and caregivers of newborns and infants. Informing new parents about risk factors and the AAP’s recommendations can be instrumental in preventing SIDS. Community pharmacists can also bolster parents’ and grandparents’ smoking-cessation efforts.

Hospital pharmacists, particularly those in the NICU or other pediatric units caring for patients younger than 12 months, also can be instrumental. They can ensure that infants in the hospital setting are sleeping in the appropriate position, both for safety purposes and to demonstrate how the parents should position the infant at home. Hospital-based pharmacists may also have the opportunity to counsel parents before their infant is discharged; if so, information on SIDS risk reduction should be communicated.

Finally, regardless of practice site or specialty, all pharmacists can educate their family and friends about these important SIDS risk-reduction strategies in order to increase public awareness and keep more infants safe.

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