Cover Article

Are you talking to parents about SIDS?

By Rachel Y. Moon, MD

Sudden infant death syndrome remains a leading cause of death in babies, but not all pediatricians are educating parents about the sleep position that substantially reduces the risk of SIDS and about other modifiable risk factors.

You are seeing a 2-month-old girl for a well-child check up. The baby is a normal, full-term infant who has been growing and developing well. When you ask the parents about the baby's sleep patterns, they tell you that she shares their bed at night. She sleeps on her side, but occasionally rolls over onto her belly.

Do you take this opportunity to talk to the parents about sudden infant death syndrome (SIDS)? If so, what do you tell them?

LEARNING OBJECTIVES

After reviewing this article the physician should be able to:

Appreciate why the prone and side positions should be avoided in healthy term infants.

Discuss common parental concerns about supine sleeping.

Identify the elements of a safe sleep environment.

Understand the implications of co-sleeping as they relate to SIDS.

Since the American Academy of Pediatrics began advocating the nonprone sleep position in 1992 (see "Getting the message out" below), the number of SIDS deaths in the US has declined by 40%—from 1.2 to approximately 0.7 deaths per 1,000 live births (Figure 1), or approximately 3,000 deaths a year.^1,2 Despite this downward trend, SIDS is still the third leading cause of death in infants, after congenital anomalies and prematurity. What's more, though studies show that parents are most likely to place their child in the recommended supine position if their baby's doctor discusses sleep position with them,³ only 70% of pediatricians and less than 30% of family practitioners do so.⁴

Getting the message out

Between 1988 and 1992, researchers in Australia, New Zealand, and Europe demonstrated that an infant's risk of SIDS decreased when she is placed on her side or back to sleep. In response to these data, the AAP released a statement in 1992 advocating a nonprone sleep position for infants.¹ In 1994, the AAP launched a national public awareness campaign, Back to Sleep, aimed at decreasing the rate of prone sleeping in the US to less than 10% for infants.² Two years later, the AAP strengthened its position by stating that, because of the instability of the side position and the possibility of an infant inadvertently rolling onto her stomach, the back position is preferable.³

In the years since the AAP's initial statement, the rate of prone sleeping has decreased from 70% to approximately 20%. The prone sleeping rate among African-American infants, however, is higher than that of other ethnic groups, and the incidence of SIDS among African-Americans is twice that of the general population (see Figure).

Recently, the AAP and the Consumer Product Safety Commission expanded their emphasis on reducing the risk of SIDS to include recommendations about all elements of a safe sleeping environment for infants,⁴ such as supine sleep position; safe cribs with a firm, snug-fitting mattress; avoidance of soft bedding; comfortable room temperature (approximately 70° F); and the absence of secondhand smoke.

SIDS rates in the US, shown in deaths for every 1,000 live births. The rate of SIDS among African-American infants is more than twice that of white infants.

Source: National Center for Health Statistics, CDC, final data, 1998

REFERENCES

1. AAP Task Force on Infant Positioning and SIDS: Positioning and SIDS. Pediatrics 1992;89:1120

2. Alexander D: Back to Sleep: A public-private partnership to reduce the risk of SIDS, American Academy of Pediatrics conference, New Orleans, 1997

3. Task Force on Infant Positioning and SIDS: Positioning and sudden infant death syndrome (SIDS): Update. Pediatrics 1996;98:1216

4. Task Force on Infant Sleep Position and Sudden Infant Death Syndrome: Changing concepts of sudden infant death syndrome: Implications for infant sleeping environment and sleep position. Pediatrics 2000;105:650

Clearly, health-care providers could be doing more to educate parents about SIDS. To that end, providers need to be better educated about the syndrome and strategies for reducing risk.

SIDS and its causes

SIDS is defined as the sudden death of a baby younger than 1 year of age, usually a previously healthy infant.⁵ It is a diagnosis of exclusion. An infant's death is attributed to SIDS only if the cause of that death remains unexplained after a thorough investigation, including complete autopsy, investigation of the death scene, and review of the infant's clinical history. Diagnoses to be considered in the differential are listed in Table 1.

TABLE 1
Differential diagnosis of SIDS

Adrenal hypoplasia

Cardiac

Cardiomyopathy

Congenital heart defect

Myocarditis

Infection

Pneumonia

Sepsis

Metabolic disorders¹

Amino acidopathies
Enzyme deficiencies, including

Carnitine uptake deficiency

Long-chain acyl-CoA dehydrogenase deficiency

Medium-chain acyl-CoA dehydrogenase deficiency

Short-chain acyl-CoA dehydrogenase deficiency

Metabolic disorders (cont.)

Glycogen storage diseases

Hyperglycinemia

Lactic acidemias

Urea cycle defects

Suffocation

Trauma (accidental and intentional)

Several misconceptions exist about what causes SIDS. The syndrome is not caused by contagious disease or immunization. Neither is it the result of external suffocation, vomiting and choking, or child abuse. It cannot be predicted by "near SIDS" events or apparent life-threatening events.

Evidence has revealed certain risk factors for SIDS, however. Researchers have developed the triple risk model (Figure 2) to describe the interaction between the three most important factors:

Age. Nine of 10 SIDS deaths occur in the first 6 months of life, most often between 2 and 4 months.

Physical vulnerability. Many infants who die of SIDS are physically more vulnerable than other babies, perhaps because of a diminished response to hypoxia and hypercarbia.

Situational risks. Infants who are physically vulnerable may die of SIDS when placed in a risky situation. A prone sleeping position, soft bedding, smoke exposure, and overheating are all risk factors. (I'll discuss these in more detail in the next section.)

Research into the cause of SIDS is focused mainly on autonomic defects. One of the more popular theories is rebreathing. Studies have shown that exhaled carbon dioxide is more likely to be trapped around the face of an infant who lies prone, especially face down, and one who sleeps with soft bedding. Instead of inhaling oxygen, such an infant rebreathes carbon dioxide and can develop hypercarbia and hypoxia.^6,7 It is hypothesized that infants who die of SIDS do not respond appropriately to hypercarbia and hypoxia and succumb.

Consequently, brainstem research has focused on autonomic control in the medulla—the portion of the brainstem believed to regulate heart rate, respiration, and arousal. Kinney and colleagues have found decreased binding at the serotonergic receptors in the brainstems of SIDS victims.⁸ This decreased serotonin binding may affect an infant's ability to respond to respiratory stress (hypercarbia and hypoxia). Here is evidence that SIDS victims have a dysfunction in the neural network.

Reducing the risk

Certain factors in addition to those included in the triple risk model increase an infant's risk of SIDS. For example, prematurity is a risk factor. The syndrome also occurs more often in male babies (1.5:1 ratio). African-American and Native American infants have a higher rate of SIDS than Caucasian, Asian, or Hispanic infants. SIDS victims are also more likely to be born to a young mother with a lower educational level. In addition, SIDS is more likely to occur in colder geographic areas and during the winter. Recent illness, such as upper respiratory infection or gastroenteritis, is commonly reported.

Risk reduction emphasizes eliminating modifiable risk factors. Prone sleeping, the most important modifiable risk factor, increases the risk of SIDS 10- to 15-fold. Although side sleeping is safer than prone sleeping, it still carries twice the risk of SIDS as supine sleeping does, largely because it is an unstable position from which infants can roll onto their stomachs.

Many theories exist as to why back sleeping reduces the risk of SIDS. It has been hypothesized, for example, that, with supine sleeping

• there is less potential for rebreathing carbon dioxide

• an infant may have better airway protective responses or cardiovascular reflexes

• the jaw is less likely to occlude the airway

• there may be less compression of the vertebral arteries supplying the brainstem

• an infant may respond more quickly to a noxious stimulus (such as hypoxia or hypercarbia), because babies who sleep on their back have a lower arousal threshold than prone sleepers

• an infant is less likely to become overheated. Overheating may lead to SIDS by increasing the arousal threshold.

Advise parents that back sleeping is the most effective measure for reducing the risk of SIDS. Also encourage parents to avoid soft bedding, including blankets, quilts, pillows, stuffed toys, sheepskins, and crib bumpers, because they may increase the potential for rebreathing carbon dioxide. If blankets are necessary, only one thin blanket should be used, and it should be tucked in so that it cannot cover the infant's head (Figure 3). In cold weather, a blanket sleeper is an alternative to a blanket. Discourage the use of waterbeds, couches, and adult beds as infant sleep surfaces; they are not required to meet child safety standards.

In utero smoke exposure and secondhand smoke exposure after birth are important risk factors for SIDS, most likely because nicotine may blunt the response to hypoxia.^9,10 The effect of smoke exposure on SIDS risk is dose dependent; the more an infant is exposed to smoke, the higher the risk.

Breastfeeding may have a protective effect against SIDS, although the reason is unclear.

It's important to emphasize that removing risk factors decreases but does not eliminate the risk of SIDS. The syndrome can strike infants who do not have any risk factors, including those who sleep on their back.

Answering the questions

Despite clear-cut evidence that back sleeping is protective, physicians, nurses, and other pediatric clinicians continue to be reluctant to fully endorse this position. No doubt, that is one reason the prone sleeping rate among infants in the US remains about 20%—approximately twice that of other developed nations that have launched campaigns similar to Back to Sleep.

To help health-care professionals understand the implications of sleep position and answer questions from parents, the following Q&As highlight some common reservations about the on-the-back position.

Are there adverse effects if an infant sleeps on her back all the time?

Surprisingly few. A large, population-based study in Great Britain found that supine sleepers had a slightly higher incidence of diaper rash (28.6% vs. 18.8%) and seborrhea (77.6% vs. 66.7%) than prone sleepers.¹¹ Supine sleepers are also less likely to sleep 14 hours a night at 6 months of age than prone sleepers, possibly because of decreased arousal thresholds. Argenta and colleagues have found positional occipital plagiocephaly (head molding) to be more common in supine sleepers.¹² This can largely be avoided if the infant spends time in the prone position while awake.

There is good evidence that supine sleepers attain early motor milestones at a later age than prone sleepers,^13,14 including those that involve use of the upper body muscles (rolling, creeping, crawling, pulling to a standing position). This observation has led to speculation that the prone position allows infants to develop these muscles at an earlier age. Differences in motor milestone attainment largely disappear, however, by the age of 1 year. In addition, placing an infant on her tummy while awake may help her develop upper-body muscle strength earlier.

Isn't an infant more likely to choke or aspirate when she sleeps on her back?

Multiple studies in countries that have had more experience with supine sleeping than the US has had have not shown any increase in the rate of choking or aspiration in the supine position.¹¹ In healthy term infants who are gaining weight and developing normally, the supine position is unlikely to increase the risk of aspiration.

I tell parents that their baby should sleep on her back at night. Since the parents are usually awake during the day, however, is it all right to recommend that the baby sleep on her belly for naps?

Infants do die of SIDS during the daytime. Never recommend prone sleeping. Infants should sleep on their back for naps and nighttime sleep.

Should an infant be on her back while she is awake as well?

Some parents have misinterpreted the sleep position guidelines to mean that babies should never be placed prone. In fact, the AAP recommends that infants spend time in the prone position every day while awake. This decreases the incidence of positional plagiocephaly and promotes development of early motor milestones.

Doesn't an infant sleep better on her tummy?

There is good evidence that infants sleep longer and more deeply when prone.¹¹ This may be precisely what makes prone sleeping dangerous: Infants may not arouse in response to hypoxia or hypercarbia. If an infant becomes accustomed to sleeping supine, she will prefer that position for sleep.

The father of a 2-month-old patient has tried to place the baby on her back since birth, but the infant still awakens every two hours. He wants to know if he can put her on her belly at night so he can get some sleep!

Infants who are unaccustomed to sleeping in the prone position are at extremely high risk of SIDS when placed prone—as much as 19 times the risk compared with nonprone sleepers.¹⁵ It is hypothesized that these infants develop upper-body muscle strength later than infants who are accustomed to prone sleeping, and they are therefore unable to lift or move their head if rebreathing occurs while prone.

Unaccustomed prone sleeping may be partly responsible for the high-risk period of 2 to 4 months of age. It may also help explain why so many SIDS deaths occur in child care (see the next question).

I have a 3-month-old patient whose mother is about to return to work. Her babysitter insists that babies do best on their stomach when they sleep. What should I tell the mother?

Advise the parent not to let the babysitter place the baby prone! A full 20% of SIDS deaths occur in child care.¹⁶ Most of those infants have older, educated, Caucasian parents, which placed them at low risk of SIDS, and most die because they are placed prone. As mentioned, placing the baby prone is especially dangerous if the infant is not accustomed to sleeping on her stomach.

When discussing sleep position with parents, emphasize that they need to discuss the subject with whomever cares for their infant—whether relative, child care provider, or babysitter.

Some parents find it easier to breastfeed their baby if she sleeps in their bed. Is co-sleeping okay?

Co-sleeping is the norm in many cultures. In the US, however, there is much controversy about the benefits and risks of this practice.¹⁷ While co-sleeping may promote breastfeeding, minimize prone infant sleeping, and increase parent and infant arousal, it may also result in overheating and excessive exposure to passive smoke. The infant may also be sleeping on a soft mattress with pillows and quilts and may be at risk of entrapment between the bed and wall or headboard.

The AAP has stated that, based on available evidence, co-sleeping does not protect against SIDS and may increase the risk of accidental suffocation.¹⁸ Nonetheless, many pediatricians and parents strongly advocate this practice. If parents choose to share their bed with their baby, they need to realize that it is not the crib that causes "crib death."

Educate parents to follow these guidelines:

• Place the infant in a supine sleep position.

• Be aware of the risk of entrapment—adult beds are not designed to meet child safety standards

• Be aware of suffocation risks. Avoid soft sleep surfaces, quilts, and pillows, for example.

• Refrain from smoking or using substances that may impair arousal (drugs, alcohol).

What about mattresses that are advertised as guarding against SIDS? And wedges that manufacturers claim keep babies on their sides?

Several manufacturers have marketed ventilated mattresses and wedges designed to keep babies supine or in the side position. There is no evidence that these products prevent SIDS; wedges have not even been studied. Most mattresses that are advertised as protecting against SIDS have been shown not to prevent rebreathing.¹⁹ In addition, there is the concern that these products can make parents complacent about measures that do reduce the risk of SIDS.

I have heard that pacifiers protect against SIDS. Should I recommend pacifiers for my patients?

Several studies have reported a two- to threefold decreased incidence of SIDS among babies who use a pacifier.^20,21 Pacifier use may lower the arousal threshold or may bring the tongue forward, opening the upper airway more. But pacifiers are also associated with shortened duration of breastfeeding, an increase in the risk of repeated episodes of otitis media, and an increase in the risk of dental malocclusion.

I'm uncomfortable telling parents to place an infant on her back; it's too extreme. Isn't side sleeping a good compromise?

If you recommend the side position to parents, keep in mind what has been borne out by research: (1) A baby who sleeps on her side is at twice the risk of SIDS as a baby who sleeps supine. The side position is an unstable one; a baby can roll into the prone position. (2) Parents whose pediatricians recommend the supine position are most likely to place their infant on her back. Parents whose pediatricians recommend a side position are least likely to place their baby supine.

The pediatrician's role

Do not assume that parents have heard about SIDS and risk reduction from books, the news, or the nursery. Parents rely upon their pediatrician's recommendations, so talk about sleep! A safe sleep environment includes the proper sleep position, avoidance of smoking, and appropriate bedding (Table 2). Organizations that can supply information about SIDS are listed in the box at left.

TABLE 2
Diminishing the risk of SIDS: What to tell parents

Multiple studies have provided ample evidence that sleeping supine dramatically lowers the risk of SIDS, and that this position has few adverse effects. So advise everyone that back is best. You may have a bigger influence on your patients than you will ever know.

REFERENCES

1. Willinger M, Hoffman HJ, Wu K-T, et al: Factors associated with the transition to nonprone sleep positions of infants in the United States: The National Infant Sleep Position Study. JAMA 1998;280:329

2. Centers for Disease Control and Prevention: Assessment of infant sleeping position—selected states, 1996. MMWR 1998;47:873

3. Willinger M, Ko C-W, Hoffman HJ, et al: Factors associated with caregivers' choice of infant sleep position, 1994-1998: The National Infant Sleep Position Study. JAMA 2000;283:2135

4. Moon RY, Gingras JL: Physician beliefs and practices regarding SIDS risk reduction strategies (abstract). Pediatr Res 2000;47:212A

5. Willinger M, James LS, Catz C: Defining the sudden infant death syndrome (SIDS): Deliberations of an expert panel convened by the National Institute of Child Health and Human Development. Pediatr Pathol 1991;11:677

6. Kemp JS: Rebreathing of exhaled gases: Importance as a mechanism for the causal association between prone sleep and sudden infant death syndrome. Sleep 1996;19:S263

7. Kemp JS, Livne M, White DK, et al: Softness and potential to cause rebreathing: Differences in bedding used by infants at high and low risk for sudden infant death syndrome. J Pediatr 1998;132:234

8. Panigraphy A, Filiano J, Sleeper LA, et al: Decreased serotonergic receptor binding in rhombic lip-derived regions of the medulla oblongata in the sudden infant death syndrome. J Neuropathol Exp Neurol 2000;59:377

9. Lewis KW, Bosque EM: Deficient hypoxia awakening response in infants of smoking mothers: Possible relationship to sudden infant death syndrome. J Pediatr 1995; 127:691

10. Froen JF, Akre H, Stray-Pedersen B, et al: Adverse effects of nicotine and interleukin-1B on autoresuscitation afer apnea in piglets: Implications for sudden infant death syndrome. Pediatrics 2000;105:URL: http://www.pediatrics.org/cgi/content/full/105/4/e52 .

11. Hunt L, Fleming P, Golding J: Does the supine sleeping position have any adverse effects on the child? I. Health in the first six months. Pediatrics 1997;100:URL: http://www.pediatrics.org/cgi/content/full/100/1/e11 .

12. Argenta LC, David LR, Wilson JA, et al: An increase in infant cranial deformity with supine sleeping position. J Craniofacial Surg 1996;7:5

13. Davis BE, Moon RY, Sachs HC, et al: Effects of sleep position on infant motor development. Pediatrics 1998; 102:1135

14. Dewey C, Fleming P, Golding J: Does the supine sleeping position have any adverse effects on the child? II.Development in the first 18 months. Pediatrics 1998; 101:URL: http://www.pediatrics.org/cgi/content/full/101/1/e5 .

15. Mitchell EA, Thach BT, Thompson JMD, et al: Changing infants' sleep position increases risk of sudden infant death syndrome. Arch Pediatr Adolesc Med 1999; 153:1136

16. Moon RY, Patel KM, Shaefer SJM: Sudden infant death syndrome (SIDS) in child care settings. Pediatrics 2000;106:295

17. Anderson JE: Co-sleeping: Can we ever put the issue to rest? Contemporary Pediatrics 2000;17:98

18. Task Force on Infant Positioning and SIDS: Does bed sharing affect the risk of SIDS? Pediatrics 1997; 100:272

19. Carolan PL, Wheeler WB, Ross JD, et al: Potential to prevent CO₂ rebreathing of commercial products marketed to reduce sudden infant death syndrome risk. Pediatrics 1999;105:774

20. Arnestad M, Andersen M, Rognum TO: Is the use of dummy or carry-cot of importance for sudden infant death? Eur J Pediatr 1997;156:968

21. Mitchell EA, Taylor BJ, Ford RPK, et al: Dummies and the sudden infant death syndrome. Arch Dis Child 1993;68:501

THE AUTHOR is Medical Director of Children's Health Center at Children's National Medical Center, Washington, D.C., and Assistant Professor, Pediatrics, at George Washington University School of Medicine and Health Sciences, Washington, D.C.

For more information about SIDS

Back to Sleep
www.nichd.nih.gov/sids
800-505-CRIB

SIDS Alliancewww.sidsalliance.org
800-221-SIDS

Association for SIDS and Infant Mortality Professionalswww.asip1.org
612-813-6285

ACCREDITATION

This activity has been planned and implemented in accordance with the Essentials and Standards of the Accreditation Council for Continuing Medical Education through the joint sponsorship of Jefferson Medical College and Medical Economics, Inc.

Jefferson Medical College of Thomas Jefferson University, as a member of the Consortium for Academic Continuing Medical Education, is accredited by the Accreditation Council for Continuing Medical Education to sponsor continuing medical education for physicians. All faculty/authors participating in continuing medical education activities sponsored by Jefferson Medical College are expected to disclose to the activity audience any real or apparent conflict(s) of interest related to the content of their article(s). Full disclosure of these relationships, if any, appears with the author affiliations at the beginning of the article.

CONTINUING MEDICAL EDUCATION CREDIT

This CME activity is designed for practicing pediatricians and other health-care professionals as a review of the latest information in the field. Its goal is to increase participants' ability to prevent, diagnose, and treat important pediatric problems.

Jefferson Medical College designates this continuing medical educational activity for a maximum of one hour of Category 1 credit towards the Physician's Recognition Award (PRA) of the American Medical Association. Each physician should claim only those hours of credit that he/she actually spent in the educational activity.

This credit is available for the period of March 15, 2001, to March 15, 2002. Forms received after March 15, 2002, cannot be processed.

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FACULTY DISCLOSURES

Jefferson Medical College, in accordance with accreditation requirements, asks the authors of CME articles to disclose any affiliations or financial interests they may have in any organization that may have an interest in any part of their article. The following information was received from the author of "Are you talking to parents about SIDS?"

Rachel Y. Moon, MD, has nothing to disclose.

 

Rachel Moon. CME: Are you talking to parents about SIDS?. Contemporary Pediatrics 2001;0:122.