The American Academy of Pediatrics (AAP) has released new recommendations for preventing sudden infant death syndrome (SIDS). The report, “The Changing Concept of Sudden Infant Death Syndrome: Diagnostic Coding Shifts, Controversies Regarding the Sleeping Environment, and New Variables to Consider in Reducing Risk,” was published in the November 2005 issue of Pediatrics.

The cause of SIDS is unknown, but the predominant hypothesis about its etiology is that certain infants, for reasons yet to be determined, may have a maldevelopment or delay in maturation of the brainstem neural network that is responsible for arousal. This change affects infants’ physiologic responses to life-threatening situations during sleep. Recent examinations of the brainstems of infants who died of SIDS have revealed deficits in serotonin receptors in a network of neurons throughout the ventral medulla. The medullary regions involved develop in midgestation from a common embryonic anlage and are thought to be involved with arousal, chemosensitivity, respiratory drive, thermoregulation, and blood pressure responses.

Despite marked reductions in SIDS rates over the past decade, it is responsible for more infant deaths in the United States than any other cause of death during infancy beyond the neonatal period. SIDS is rare during the first month of life, increases to a peak between two and three months of age, and then decreases.

The following factors increase the risk of SIDS: prone sleep position, sleeping on a soft surface, maternal smoking during pregnancy, overheating, late or no prenatal care, young maternal age, preterm birth, low birth weight, and male sex. Black, American Indian, and Alaskan Native children have rates of SIDS that are two to three times the national average.

The slowing in the decline of the SIDS rate coincides with a slowing in the reduction of prone positioning of infants during sleep. Ongoing national sampling has shown that the prevalence of prone positioning in the United States decreased from 70.0 percent in 1992 to 11.3 percent in 2002 and increased slightly to 13.0 percent in 2004. Racial disparity in the prevalence of prone positioning may be contributing to the difference in SIDS rates between black and white infants; prone positioning is more common in black infants than in white infants (21 versus 11 percent). Additional work in promoting appropriate infant sleep positions and sleeping-environment conditions may be necessary to resume the previous rate of decline for SIDS.

Despite the decrease in the rate of SIDS and the decreased frequency of prone sleeping, the proportion of SIDS deaths occurring in child care remained constant between 1996 and 1998. In the United States, approximately 20 percent of SIDS deaths occur while the infant is in the care of a nonparental caregiver. Many child-care deaths have been associated with the prone sleep position, especially when the infant is unaccustomed to being placed in that position. It is often a nonparental caregiver who places the infant in an unaccustomed prone position, which increases the risk of SIDS by as much as 18-fold. A 1996 study revealed that 43 percent of licensed child-care centers were unaware of the relationship between SIDS and infant sleep position, and subsequent surveys of child-care centers have found that, despite increased awareness of this relationship, 20 to 28 percent of centers continue to place infants to sleep in the prone position. Licensed child-care centers seldom have adequate regulations for safe sleeping, and most states do not have safe-sleep regulations for child-care providers. In addition, many infants are cared for by relatives and nonlicensed caregivers (e.g., babysitters, nannies, unregulated family child-care homes) who still may be unaware of the importance of supine sleeping.

Studies have shown that infants who die from SIDS are more likely to have used a pillow or soft mattress, to have been found with their nose and mouth completely covered by bedding, or to have assumed a face-down posture. A case-control study confirmed the strong association between SIDS and the use of soft bedding (odds ratio [OR]: 5.1) or pillows (OR: 2.5), independent of prone sleep position (adjusted OR: 5.2 and 2.8, respectively). A strong interaction was found between prone sleep position and soft bedding surface, with an adjusted OR of 21.0, indicating that these two factors together are very hazardous. Soft surfaces also have been implicated in infant deaths occurring on adult beds.

Bed sharing between an infant and adult is controversial. Although electrophysiologic and behavioral studies offer a strong case for its effect in facilitating breastfeeding and the enhancement of maternal-infant bonding, epidemiologic studies of bed sharing have shown that it can be dangerous under certain conditions. Several case series of accidental suffocation or death from undetermined cause also suggest that bed sharing is hazardous. The risk of SIDS seems to be particularly high when there are multiple bed sharers and also may be increased when the bed sharer has consumed alcohol or is overtired. The risk of SIDS also is higher when bed sharing occurs with infants younger than 11 weeks and when the bed is shared for more than one hour each night. There is growing evidence that room sharing (i.e., infant sleeping in the parent’s room) without bed sharing is associated with a reduced risk of SIDS.

Several studies have reported that the use of a pacifier has a protective effect on the incidence of SIDS. The mechanism for this effect is unclear, but several possibilities, such as lowered arousal thresholds, have been proposed. Although several studies have shown a correlation between pacifiers and reduced breastfeeding duration, the results of well-designed, randomized, clinical trials indicate that pacifiers do not cause shortened breastfeeding duration for term and preterm infants. Furthermore, the American Academy of Pediatric Dentistry concluded that “nonnutritive sucking behaviors (i.e., finger or pacifier) are considered normal in infants and young children … and in general, sucking habits in children to the age of five are unlikely to cause any long-term problems.” Pacifier use is associated with a slightly increased risk of otitis media, but the incidence is generally lower in the first year of life, especially the first six months, when the risk of SIDS is the highest.

Based on this evidence, the AAP made the following recommendations:

• Infants should be placed for sleep in a supine position (wholly on the back) for every sleep. Side sleeping is not as safe as supine sleeping and is not advised.

• Soft materials or objects such as pillows, quilts, comforters, or sheepskins should not be placed under a sleeping infant. A firm crib mattress, covered by a sheet, is the recommended sleeping surface.

• Soft objects, including stuffed toys and soft bedding, should be kept out of an infant’s sleeping environment. If bumper pads are used in cribs, they should be thin, firm, well secured, and not “pillow-like.” In addition, loose bedding such as blankets and sheets may be hazardous. If blankets are used, they should be tucked in around the crib mattress so that the infant’s face is less likely to become covered. One strategy is to make up the bedding so that the infant’s feet are able to reach the foot of the crib, with the blankets tucked in around the crib mattress and reaching only to the level of the infant’s chest. Another strategy is to use sleep clothing designed for warmth with no other covering of the infant to avoid the hazard of head covering.

• Women should not smoke during pregnancy and should avoid exposing infants to secondhand smoke. Maternal smoking during pregnancy has emerged as a major risk factor in almost every epidemiologic study of SIDS. Smoke in the infant’s environment after birth has emerged as a separate risk factor in a few studies, although separating this variable from maternal smoking before birth is problematic.

• A separate but proximate sleeping environment is recommended. The risk of SIDS is reduced when the infant sleeps in the same room as the mother. A crib, bassinet, or cradle that conforms to the safety standards of the Consumer Product Safety Commission and ASTM (formerly the American Society for Testing and Materials) is recommended. “Cosleepers” (i.e., infant beds that attach to the mother’s bed) provide easy access for the mother to the infant, especially for breastfeeding, but safety standards for these devices have not yet been established. Infants may be brought into the parent’s bed for nursing or comforting but should be returned to their own crib or bassinet when the parent is ready to return to sleep. The infant should not be brought into bed when the parent is excessively tired or using medications or substances that could impair his or her alertness.

• Consider offering a pacifier at nap time and bedtime. Until evidence dictates otherwise, the use of a pacifier throughout the first year of life is recommended according to the following procedures: the pacifier should be used when placing the infant down for sleep and should not be reinserted once the infant falls asleep; if the infant refuses the pacifier, he or she should not be forced to take it; pacifiers should not be coated in any sweet solution; pacifiers should be cleaned often and replaced regularly. For breastfed infants, pacifier introduction should be delayed until one month of age to ensure that breastfeeding is firmly established.

• The infant should be lightly clothed for sleep, and the bedroom temperature should be kept comfortable for a lightly clothed adult. Overbundling should be avoided, and the infant should not feel hot to the touch.

• Commercial devices marketed to reduce the risk of SIDS should be avoided. Although various devices have been developed to maintain sleep position or reduce the risk of rebreathing, none has been tested sufficiently.

• Home monitors should not be used to reduce the risk of SIDS. Electronic respiratory and cardiac monitors are available to detect cardiorespiratory arrest and may be of value for home monitoring of selected infants who are deemed to have extreme cardiorespiratory instability. However, there is no evidence that use of such home monitors decreases the incidence of SIDS. Furthermore, there is no evidence that infants at increased risk of SIDS can be identified by inhospital respiratory or cardiac monitoring.

• To avoid the development of positional plagiocephaly, “tummy time” should be encouraged when the infant is awake and observed. This also will enhance motor development. Infants should not spend excessive time in car-seat carriers and “bouncers,” in which pressure is applied to the occiput. Instead, upright “cuddle time” should be encouraged. The supine head position should be altered during sleep. Techniques for accomplishing this include placing the infant to sleep with the head to one side for a week and then changing to the other side. Consideration should be given to early referral of infants with plagiocephaly when it is evident that conservative measures have been ineffective. In some cases, orthotic devices may help avoid the need for surgery.

• Public education should be intensified for secondary caregivers (e.g., child-care providers, grandparents, foster parents, baby sitters). Education should be focused on black, American Indian, and Alaskan Native populations.