sudden infant death syndrome
Sudden Infant Death Syndrome
Sudden infant death syndrome
Sudden infant death syndrome (SIDS) is the sudden, unexpected death of a seemingly normal, healthy infant under one year of age that remains unexplained after a thorough postmortem investigation, including an autopsy and a review of the case history.
SIDS is a defined medical disorder that is listed in the International Classification of Diseases, 9th Revision (ICD-9). The first published research about sudden infant death appeared in the mid-nineteenth century. Since then, researchers and healthcare providers have struggled to define the syndrome and determine its causes. The key characteristics of SIDS include:
- infant less than one year of age
- infant seemingly healthy (no preceding symptoms)
- complete investigation fails to find a cause of death
- no associated child abuse or illness
In the United States, SIDS was the third leading cause of postneonatal deaths (those occurring between the ages of 28 days and one year) in 2001. According to the National Center for Health Statistics, 2,234 infants in the United States died of SIDS in 2001, or 8.1 percent of total infant deaths. (In the late 1990s, many sources placed the annual total number of deaths as high as 6,000 due to possible under-reporting.) Ninety percent of SIDS deaths occur during the first six months of life, mostly between the ages of two and four months. SIDS also occurs about 1.5 times more frequently in boys than girls. The rate of SIDS in African-American infants is twice as high as that of Caucasians, a fact often attributed to the lower quality of prenatal care received by many African-American mothers.
Causes and symptoms
Studies have identified many risk factors for SIDS, but the actual cause of the disorder remains a mystery. Although investigators are still not sure whether the immediate cause of SIDS deaths is due to respiratory failure or cardiac arrest, patterns of infant sleep , breathing, and arousal are a major focus of research in the early 2000s. It is known that young infants often stop breathing for short periods of time, then gasp and start again. Some researchers and physicians believe that SIDS involves a flaw in the mechanism that is responsible for resumption of breathing.
Aside from its occurrence during sleep, the other most striking feature of SIDS is its narrow age distribution, which has prompted researchers to examine the developmental changes that take place between the ages of two and four months, especially between the ages of two and four months, when most SIDS deaths occur. A growing number of experts believe that rather than a single cause, there are a number of different conditions that can cause or contribute to SIDS. This picture is complicated still further by the interaction of possible physical abnormalities with a number of environmental and developmental factors known to increase the risk of SIDS. Premature infants and low birth weight babies in general are known to be at increased risk of developing SIDS, as are infants born to teenage mothers, poor mothers, and mothers who for any reason have had inadequate prenatal care. Other risk factors include maternal smoking during pregnancy, exposure to smoking in the home after birth, formula feeding rather than breastfeeding, and prior death of a sibling from SIDS (although this is thought to be due to shared environmental risk factors rather than genetic predisposition). Many SIDS deaths occur in babies who have recently had colds (a possible reason that SIDS is most prevalent in winter, the time when upper respiratory infections are most frequent).
As of 2004, the most significant risk factor discovered for SIDS was placing babies to sleep in a prone position (on their stomachs). Studies have reported that anywhere from 28 percent to 52 percent of infants who die of SIDS are found lying face down. Another finding reinforcing the connection between SIDS and prone-sleeping is the fact that SIDS rates are higher in Western cultures, where women have traditionally placed children on their stomachs, than in Eastern ones, where infants usually sleep on their backs. The cause-effect relationship between prone-sleeping and SIDS is not fully understood. However, it is known that when infants sleep on their backs they are more prone to arousal, and SIDS is often thought to involve a failure to rouse from sleep. In addition, prone-sleeping raises a baby's temperature, which is another risk factor for the disorder.
When to call the doctor
Parents or caregivers should immediately call for emergency care if a child is found not breathing or without a pulse or is unable to be aroused from sleep.
In most cases, three techniques are used in an attempt to determine the cause of an infant's death. These are:
- Death scene investigation. A thorough examination of the scene of death, including recording baby's position, collecting items from the surrounding area, and interviewing family members and/or caregivers, can sometimes point to an external cause of death.
- Autopsy. The autopsy, usually performed by a medical examiner or coroner, focuses on finding any identifiable cause of death. While parents may reject the idea of an autopsy because they feel it violates their infant's remains, it is often the only tool that can definitively rule out other potential causes of death.
- Review of family history. Healthcare providers or police interview parents and/or caregivers in order to determine the child's medical and family history, in an attempt to rule out possible illness, child abuse, or other cause of death.
Because SIDS affects seemingly healthy infants, and death is the first symptom of the disorder, it is not possible to treat an infant who is truly affected by SIDS. If life support is implemented and the child is resuscitated, emergency care will be provided in an attempt to stabilize the child. Healthcare personnel perform a complete medical exam and record the child's medical history to exclude other potential causes.
By definition the prognosis for babies affected by SIDS is invariably death. In some rare cases, emergency care providers are able to resuscitate an infant who is seemingly lifeless; the prognosis remains poor in these cases.
In the 1990s a number of countries initiated campaigns aimed at getting parents to put their infants to sleep on their backs or sides. In the United States, the American Academy of Pediatrics (AAP) in 1992 issued an official recommendation that infants be put to bed on their backs (supine position) or on their sides (lateral position). In 1994 the Public Health Service launched its "Back to Sleep" campaign, targeting parents, other care givers, and healthcare personnel with brochures advocating supine or lateral infant sleeping and also including information about other risk factors for SIDS. By the mid-1990s it was apparent that this and similar campaigns worldwide had had a significant—in many cases dramatic—impact in reducing the number of deaths from SIDS. In a number of countries the incidence of SIDS dropped by 50 percent or more. SIDS deaths in Great Britain were reduced by 91 percent between 1989 and 1992; in Denmark they declined by 72 percent between 1991 and 1993; and they were reduced by 45 percent in New Zealand between 1989 and 1992.
In the United States, the AAP recommendations reduced the incidence of front-sleeping in infants from over 70 percent in 1992 to 24 percent in 1996. A decline in SIDS rates, already observed in the 1980s, tripled its previous pace between 1990 and 1994, with SIDS deaths falling 10 to 15 percent between 1992 and 1994. Links between SIDS and other aspects of an infant's sleep environment have also emerged. The best known is the finding that soft, padded sleep surfaces can endanger infants by obstructing breathing or creating air pockets that trap their expelled carbon dioxide, which they can then inhale.
Some research also suggests that co-sleeping (having an infant sleep with the mother in her bed) can help regulate an infant's sleep pattern in ways that reduce the risk of SIDS. (Like supine infant sleeping, co-sleeping is also prevalent among Asian populations, which have a low incidence of SIDS.) Infants who share their mothers' beds become accustomed to frequent minor arousals when the mother shifts position, and their own sleep tends to be lighter and more even than that of infants who sleep alone in their cribs and are more prone to the heavier, but sporadic, breathing that stops and then starts up again with a gasp. Experts speculate that this lighter sleep not only makes it less likely for an infant to stop breathing but also that such an infant, with the "practice" gained from more frequent arousals every night, can be aroused more easily when any respiratory distress does occur. In addition, infants who co-sleep with their mothers are naturally more likely to sleep on their backs or sides, which also reduces the risk of SIDS.
In December 1996 the AAP issued the following updated recommendations regarding infant sleep:
- Infants should be put to sleep in a nonprone position. The supine position (on their backs) is safest, but sleeping on their sides can also significantly reduce the risk of SIDS. When infants sleep on their sides, the bottom arm should be extended to prevent them from rolling over on to their stomachs.
- Soft sleeping surfaces should be avoided, and a sleeping infant should not be placed on soft objects such as pillows or quilts.
- It may be better for parents, with the guidance of their pediatrician, to depart from these recommendations in the case of infants with certain health problems, such as gastroesophageal reflux (GER).
- Infants should spend some time lying on their stomachs when they are awake and supervised by an adult.
Other precautions parents can take include obtaining adequate prenatal care; avoiding exposing infants to cigarette smoke, either pre- or postnatally; breastfeeding instead of formula feeding; and not allowing an infant to become overheated while sleeping. Another measure taken by some parents is the use of a portable battery-operated monitor that sounds an alarm in response to significant deviations in infants' respiration or heart rates while they are asleep. Monitoring is based on the belief that if parents can quickly reach an infant who has stopped breathing, they can either get him breathing again themselves or call for emergency assistance. There has been no substantiated link between monitoring and the decrease in SIDS, and infants have, in fact, died while being monitored. Nevertheless, monitors provide peace of mind for many parents, especially those who have already lost an infant to SIDS or whose baby has special risk factors for the disorder. Medical opinion is generally in favor of monitoring only for newborns who have had episodes of apnea (cessation of breathing) or for any infant who has had a precipitous, life-threatening interruption of breathing or cardiovascular function.
Losing a child—a traumatic experience for any parent—is especially difficult for those who lose a child to SIDS because the death is so sudden and its cause can often not be determined. Parents of a child who dies of SIDS do not gain a medical explanation of their infant's death. Although such an understanding does not lessen their loss, it can serve an important function in the healing process, one that SIDS parents do not have. In addition to the emotions that normally accompany grief, such as denial, anger, and guilt, SIDS parents may experience certain other reactions unique to their situation. They may become fearful that another unexpected disaster will strike them or members of their families. After the death of a child from SIDS, parents often become over-protective of the infant's older siblings and of any children born subsequently. Some fear having another child, due to misgivings that the tragedy they have experienced may repeat itself. Parents of children who die of SIDS often make major changes in their lives during the period following the death, such as relocating or changing jobs, as a way to avoid confronting painful memories or as a way to protect themselves against the SIDS death of another baby by changing the circumstances of their lives as much as possible.
SIDS deaths place a great strain on marriages. Parents' individual ways of coping with their grief may prevent them from giving each other the support they need, creating an emotional distance between them. Nevertheless, the divorce rate among SIDS parents appears to be no higher than that for the general population, and in one survey half the respondents reported that their marriages had ultimately been strengthened by the experience.
A SIDS death also has a significant effect on the infant's siblings. Young children often experience developmental regressions in toilet training or other areas. Some fear going to sleep, which they associate with the death of their baby brother or sister. As with any death in the family, children need to be reassured that they are not guilty in any way. Many pose difficult questions to their parents, wanting to know why the baby died or where he has gone, or even whether they are going to die, too. Children may also come to feel jealous of the attention paid to the infant who has died or resentful of the disruption the death has caused in their family's life. Most parents report that their way of caring for their remaining children changes after the family experiences a SIDS death. Having young children (or infants born later on) sleep with them at night makes some parents feel more confident of preventing a second tragedy from occurring. In addition to overprotecting their children and worrying about their health, SIDS parents may also spoil them and find it hard to say no to their requests. On the positive side, many parents simply value their remaining children more, spend more time with them, and become closer to them. In a minority of cases, however, the reverse happens, and parents feel emotionally distant from their surviving children. In addition, fear of being hurt sometimes makes it difficult for some parents to bond with babies born later.
Many parents of infants who die of SIDS are helped by participating in local support groups, where they can share their feelings and experiences with others who have undergone the same experience. Counseling can also be beneficial, especially with a mental health professional experienced in dealing with parental grief.
Apnea —The temporary absence of breathing. Sleep apnea consists of repeated episodes of temporary suspension of breathing during sleep.
Co-sleeping —Having an infant sleep with the mother in her bed.
Gastroesophogeal reflux —Backward flow of stomach contents into the esophagus.
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Mawhiney, Robert. S.I.D.S.: New Research into Sudden Infant Death Syndrome—Cause and Effect. Philadelphia: Xlibris Corp., 2003.
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American Academy of Pediatrics. 141 Northwest Point Blvd., Elk Grove Village, IL 60007–1098. Web site: <www.aap.org>.
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SIDS Alliance. 1314 Bedord Ave., Suite 210, Baltimore, MD 21208. Web site: <www.sidsalliance.org>.
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Stephanie Dionne Sherk
Sudden Infant Death Syndrome
Sudden Infant Death Syndrome
In typical cases of sudden infant death syndrome (SIDS), an infant between the ages of two to four months is found dead with no warning, frequently during a period of sleep. Because the typical victims are previously healthy infants with no record of any serious medical problems, their sudden death is all the more shocking and devastating. Some have said that this type of death is "a cosmic slap in the face" to parents, grandparents, other adults, and siblings who had previously delighted in the child's birth and growth, and plans for his or her future.
Sudden infant death syndrome—called "SIDS" by many professionals, but also termed "crib death" in the United States or "cot death" in some other English-speaking countries—is "the sudden death of an infant under one 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, James, and Catz 1991, p. 681).
Three aspects of this definition are worth noting. First, an accurate diagnosis of this syndrome requires a thorough investigation, including an autopsy (preferably performed by a medical examiner or forensic pathologist who is experienced in diagnosing infant deaths), along with a careful examination of the history and circumstances behind the death (including interviews of parents and others involved in the care of the infant, collection of items from the scene of death, and meticulous evaluation of all of the information obtained). Hasty or incomplete diagnoses can sometimes confuse SIDS with deaths resulting from child abuse or other causes. Such errors can compound burdens placed upon parents and other survivors of SIDS if they are wrongly accused of child abuse, just as they may cloak abusive situations under the more benign diagnosis of SIDS.
Second, a diagnosis of SIDS is essentially an exclusionary diagnosis, one that is made by ruling out all other possible causes and then recognizing the distinctive patterns of this cluster of events. A "syndrome" is precisely a familiar constellation of events arising from an unknown cause. Third, although no definitive diagnostic indicators unmistakably identify recognized abnormalities in SIDS that are sufficient to cause death, there nevertheless are some biological, clinical, and historical or circumstantial markers commonly found in this syndrome. These common but not universal markers include:
- • tiny red or purple spots (minute hemorrhages or petechiae) on the surface of the infant's heart, in its lungs, and in its thymus;
- • an increased number of star-shaped cells in its brain stem (brain-stem gliosis);
- •clinical suggestions of apnea or pauses in breathing and an inability to return to normal breathing patterns; and/or
- • circumstantial facts such as a peak incidence of SIDS at two to four months of age, which declines to almost nonoccurrence beyond one year of age.
Markers such as these, when identified by a competent, thorough, and experienced physician, justify recognizing SIDS as an official medical diagnosis of death.
During most of the 1980s, SIDS accounted for the deaths of approximately 5,000 to 6,000 infants per year in the United States. From 1988 to 1999, however, SIDS rates fell by more than 52 percent in the United States, and the number of SIDS deaths declined to 2,648 in 1999.
In terms of the overall number of live births each year, SIDS is the leading cause of death in the United States among infants between one month and one year of age. For all infants less than one year of age, SIDS is the third-leading cause of death, following only congenital anomalies and short gestation/low birthweight.
Researchers have drawn attention to other aspects of the incidence of SIDS deaths, but those variables have not yet been sufficient to establish differential diagnoses, screening procedures, or preventive measures for SIDS. In fact, SIDS is a sudden and silent killer, often associated with sleep, but apparently involving no suffering. Characteristically, SIDS deaths show a pronounced peak during the colder months of the year: January through March in the United States or six months later in the southern hemisphere. Epidemiological studies suggest that SIDS is somehow associated with a detrimental prenatal environment, but infants who are at risk for SIDS cannot be distinguished from those who are at risk for many other health problems. In general, at-risk infants include those with low birthweight or low weight gain and those whose mothers are less than twenty years of age, were anemic, had poor prenatal care, smoked cigarettes or used illegal drugs during pregnancy, and had a history of sexually transmitted disease or urinary tract infection. But none of these factors is sufficient in predicting how, when, why, or if SIDS will occur.
In terms of social, racial, or other categories, SIDS appears in families from all social groups. Approximately 60 percent of all SIDS deaths are those of male infants. The largest number of SIDS deaths (approximately 70%) occurs in infants between two and four months of age, with most SIDS deaths (approximately 90%) taking place by six months of age.
The "Back to Sleep Campaign"
In the early 1990s research suggested that infants might be at less risk for SIDS if they were laid to sleep on their backs (supine) or sides rather than on their stomachs (prone). That idea ran contrary to familiar advice that favored infants sleeping prone in order to reduce the risk that they might regurgitate or spit up fluids, aspirate them into their airway, and suffocate. Some health care professionals and family members still seem to believe that prone sleeping is best for an infant, but the new research suggested that infants who sleep on their stomachs are at far greater risk of SIDS than they are of other problems.
Accordingly, in April 1992, the American Academy of Pediatrics (AAP) Task Force on Infant Sleep Position concluded it was likely that infants who sleep on their backs and sides are at least risk for SIDS when all other circumstances are favorable (e.g., when sleeping on a firm mattress without overheating, loose bed covers, or soft toys nearby). As a result, the AAP recommended that "healthy infants, when being put down for sleep, be positioned on their side or back."
In June 1994 a national "Back to Sleep Campaign" was initiated in the United States. A joint effort of the U.S. Public Health Service, the AAP, the SIDS Alliance, and the Association of SIDS and Infant Mortality Programs, the campaign seeks to employ literature, the media, and other avenues to raise professional and public awareness about the importance of sleep positioning as a way to reduce SIDS. SIDS Resources, Inc., in Missouri, provided one local example of how this campaign can be implemented in a simple but effective way by developing and distributing to new mothers tiny T-shirts for infants with the legend on the front of their shirt, "THIS SIDE UP . . . while sleeping."
Subsequently, the AAP revised and strengthened its recommendation by emphasizing that positioning infants on their backs is the preferred position for their sleep at night and during naps. The AAP acknowledged that it is acceptable to allow infants to sleep on their sides because that is significantly better for them than sleeping on their stomachs, but side sleeping without proper support is a less stable position for an infant and thus not as desirable as back sleeping.
Dramatic and sustained reductions in SIDS deaths in the United States and many other countries are associated with initiatives like the "Back to Sleep Campaign." Unfortunately, they have not applied equally to all racial and cultural groups in America. For example, it has been noted that African-American mothers are "still significantly more likely to place their infants prone" (Willinger, et al. 1998, p. 332). This reluctance to place infants on their backs for sleep appears to be directly correlated with less significant declines in SIDS death rates among African-American infants than among infants in other groups in American society.
Research on SIDS is extraordinarily difficult, facing many problems that have long frustrated scientific investigators. For example, in SIDS there are no living patients to study because the first symptom of SIDS is a dead baby. In addition, risk factors for SIDS are not strong or specific enough to permit identification of high-risk groups as subsets of the general infant population in which the natural history of a disease can be followed with smaller numbers of subjects. And there are no naturally occurring animal models for SIDS. As a result, SIDS is currently unpredictable and unpreventable, although it is possible to modify some risk factors for SIDS deaths.
Most researchers now believe that babies who die of SIDS are born with one or more conditions that make them especially vulnerable to stresses that occur in the normal developmental life of an infant, including both internal and external influences. The leading hypothesis for study is delayed development of arousal, cardiorespiratory control, or cardiovascular control.
Meanwhile, research based on epidemiology and pathology has dispelled numerous misleading and harmful myths about SIDS (e.g., it is not contagious and does not run in families) and has also ruled out many factors that have been thought at various times to be the causes of SIDS. For instance, it is known that SIDS is not the result of child abuse. Likewise, SIDS is not caused by vomiting and choking, minor illnesses such as colds or infections, or immunizations such as those involved in DPT (diphtheria, pertussis, and tetanus) vaccines. Nor is SIDS the cause of every sudden infant death.
Any sudden, unexpected death threatens one's sense of safety and security because it forces one to confront one's own mortality. This is particularly true in an infant death because the death of a very young child seems an especially cruel disruption of the natural order: It seems inconceivable to most people, especially to new parents, that children should suddenly die for no apparent reason. The lack of a discernible cause, the suddenness of the tragedy, and the involvement of the legal system also help to make a SIDS death especially difficult for all those it touches, leaving a great sense of loss and a need for understanding.
As a result, in addition to tasks that all bereaved persons face in coping with grievous personal loss, those who have lost a child to SIDS face additional challenges. No postdeath intervention can be expected simply to dismiss such difficult challenges. However, classification of an infant's death as an instance of SIDS—naming it as an occurrence of a recognizable syndrome—may help provide some partial framework for understanding. This diagnosis can also go a long way toward easing the unwarranted guilt of survivors who might mistakenly imagine that they had somehow contributed to the death or that they could have done something to prevent it. SIDS survivors, especially parents and grandparents, are likely to require much information about the syndrome and extended support in their bereavement. Contact with others who have experienced a similar death may be particularly useful. Explaining the death to a surviving child or subsequent sibling will demand empathy and skill.
Education and Support
There is a great need at many levels in society for SIDS education and support. First responders (i.e., emergency medical personnel, dispatchers, police officers, and firefighters), day-care providers, funeral directors, and the clergy need to understand the differences between their clinical, legal, and human tasks. They must also recognize the different priorities that pertain to preventive tasks on the one hand and to emergency or follow-up tasks on the other. Counselors of all kinds must appreciate that those who are bereaved by SIDS are likely to have distinctive needs for information both about SIDS and about their own grief reactions and coping processes. For example, counselors will want to know how to validate the experiences of SIDS survivors, enable them to obtain access to medical resources, and introduce them to other SIDS survivors. Further, counselors will want to help those affected by SIDS to be patient with others experiencing their own unique bereavement from the same loss, and to assist them in moving on. Adult survivors may need help in explaining SIDS losses and grief reactions to siblings and other children, and in addressing questions related to a possible subsequent pregnancy. SIDS support groups and bereavement-support groups in other settings (e.g., a church or hospice program) may need guidance in meeting the special needs of those touched by SIDS.
See also: Grief: Child' s Death, Family; Mortality, Infant
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CHARLES A. CORR DONNA M. CORR
Sudden Infant Death Syndrome
Sudden Infant Death Syndrome
Sudden infant death syndrome (SIDS) is the unexplained death without warning of an apparently healthy infant, usually during sleep.
Also known as crib death, SIDS has baffled physicians and parents for years. In the 1990s, advances have been made in preventing the occurrence of SIDS, which killed more than 4,800 babies in 1992 and 3,279 infants in 1995. Education programs aimed at encouraging parents and caregivers to place babies on their backs and sides when putting them to bed have helped contribute to a lower mortality rate from SIDS.
In the United States, SIDS strikes one or two infants in every thousand, making it the leading cause of death in newborns. It accounts for about 10% of deaths occurring during the first year of life. SIDS most commonly affects babies between the ages of two months and six months; it almost never strikes infants younger than two weeks of age or older than eight months. Most SIDS deaths occur between midnight and 8 A.M.
Causes and symptoms
Risk factors for SIDS
The exact causes of SIDS are still unknown, although studies have shown that many of the infants had recently been under a doctor's care for a cold or other illness of the upper respiratory tract. Most SIDS deaths occur during the winter and early spring, which are the peak times for respiratory infections. The most common risk factors for SIDS include:
- sleeping on the stomach (in the prone position)
- mother who smokes during pregnancy ; smokers are as much as three times more likely than nonsmokers to have a SIDS baby
- the presence of passive smoke in the household
- male sex; the male/female ratio in SIDS deaths is 3:2;
- belonging to an economically deprived or minority family
- mother under 20 years of age at pregnancy
- mother who abuses drugs
- mother with little or no prenatal care
- prematurity or low weight at birth
- family history of SIDS
Most of these risk factors are associated with significantly higher rates of SIDS; however, none of them are exact enough to be useful in predicting which specific children may die from SIDS.
Ten Leading Causes Of Infant Death (U.S.)
Sudden Infant Death Syndrome (SIDS)
Respiratory Distress Syndrome
Problems related to complications of pregnancy
Complications of placenta, cord, and membrane Accidents
Intrauterine hypoxia and birth asphyxia
Theories about SIDS
MEDICAL DISORDERS. Currently, it is not known whether the immediate cause of death from SIDS is a heart problem or a sudden interruption of breathing. The most consistent autopsy findings are pinpoint hemorrhages inside the baby's chest and mild inflammation or congestion of the nose, throat, and airway. Some doctors have thought that the children stop breathing because their upper airway gets blocked. Others have suggested that the children have an abnormally high blood level of the chemicals that transmit nerve impulses to the brain, or that there is too much fetal hemoglobin in the blood. A third theory concerns the possibility that SIDS infants have an underlying abnormality in the central nervous system. This suggestion is based on the assumption that normal infants sense when their air supply is inadequate and wake up. Babies with an abnormal nervous system, however, do not have the same alarm mechanism in their brains. Other theories about the cause of death in SIDS include immune system disorders that cause changes in the baby's heart rate and breathing patterns during sleep, or a metabolic disorder that causes a buildup of fatty acids in the baby's system.
PHYSICAL SURROUNDINGS. A recent theory proposes that SIDS is connected to the child's rebreathing of stale air trapped in soft bedding. In addition to the infant's sleeping in the prone position, pillows, sheepskins, and other soft items may contribute to trapping air around the baby's mouth and nose, which causes the baby to breathe in too much carbon dioxide and not enough oxygen. Wrapping a baby too warmly has also been proposed as a factor.
The diagnosis of SIDS is primarily a diagnosis of exclusion. This means that it is given only after other possible causes of the baby's death have been ruled out. Known risk factors aid in the diagnosis. Unlike the pattern in other diseases, however, the diagnosis of SIDS can only be given post-mortem. It is recommended that all infants who die in their sleep receive an autopsy to determine the cause. Autopsies indicate a definite explanation in about 20% of cases of sudden infant death. In addition, an autopsy can often put to rest any doubts the parents may have. Investigation of the location of the death is also useful in determining the child's sleeping position, bedding, room temperature, and similar factors.
There is no treatment for SIDS, only identification of risk factors and preventive measures. The baby's parents may benefit from referral to counseling and support groups for parents of SIDS victims.
Congenital— Existing or present at the time of birth.
Crib death— Another name for SIDS.
Prone— Lying on the stomach with the face downward.
Supine— Lying on the back with the face upward.
SIDS appears to be at least partly preventable, which has been shown by a substantial decrease in the case rate. The following are recommended as preventive measures:
- Sleep position. The United States Department of Health and Human Services initiated a "Back-to-Sleep" campaign in 1994 to educate the public about sleep position. Prior to that time, an estimated 70% of infants slept on their stomachs, since parents had been taught that a "back down" position contributed to choking during sleep. There are some conditions for which doctors will recommend the prone position, but for normal infants, side or back (supine) positions are better. When placing an infant on his or her side, the parent should pull the child's lower arm forward so that he or she is less likely to roll over onto the stomach. When babies are awake and being observed, they should be placed on their stomachs frequently to aid in the development of the muscles and skills involved in lifting the head. Once a baby can roll over to his or her stomach, he or she has developed to the point where the risk of SIDS is minimal.
- Good prenatal care. Proper prenatal care can help prevent the abnormalities that put children at higher risk for SIDS. Mothers who do not receive prenatal care are also more likely to have premature and low birth-weight babies. Expectant mothers should also be warned about the risks of smoking, alcohol intake, and drug use during pregnancy.
- Proper bedding. Studies have shown that soft bedding, such as beanbags, waterbeds and soft mattresses, contributes to SIDS. Babies should sleep on firm mattresses with no soft or fluffy materials underneath or around them—including quilts, pillows, thick comforters or lambskin. Soft stuffed toys should not be placed in the crib while babies sleep.
- Room temperature. Although babies should be kept warm, they do not need to be any warmer than is comfortable for the caregiver. An overheated baby is more likely to sleep deeply, perhaps making it more difficult to wake when short of breath. Room temperature and wrapping should keep the baby warm and comfortable but not overheated.
- Diet. Some studies indicate that breastfed babies are at lower risk for SIDS. It is thought that the mother's milk may provide additional immunity to the infections that can trigger sudden death in infants.
- Bedsharing with parents. Opinions differ on whether or not bedsharing of infant and mother increases or decreases the risk of SIDS. Bedsharing may encourage breastfeeding or alter sleep patterns, which could lower the risk of SIDS. On the other hand, some studies suggest that bedsharing increases the risk of SIDS. In any case, mothers who choose to bring their babies to bed should observe the following cautions: Soft sleep surfaces, as well as quilts, blankets, comforters or pillows should not be placed under the baby. Parents who sleep with their infants should not smoke around the baby, or use alcohol or other drugs which might make them difficult to arouse. Parents should also be aware that adult beds are not built with the same safety features as infant cribs.
- Secondhand smoke. It is as important to keep the baby's environment smoke-free during infancy as it was when the mother was pregnant with the baby.
- Electronic monitoring. Electronic monitors are available for use in the home. These devices sound an alarm for the parents if the child stops breathing. There is no evidence, however, that these monitors prevent SIDS. In 1986, experts consulted by the National Institutes of Health (NIH) recommended monitors only for infants at risk. These infants include those who have had one or more episodes of breath stopping; premature infants with breathing difficulties; and babies with two or more older siblings that died of SIDS. Parents who use monitors should know how to use them properly and what to for the baby if the alarm goes off.
- Immunizations. There is no evidence that immunizations increase the risk of SIDS. In fact, babies who receive immunizations on schedule are less likely to die of SIDS.
National Institute of Child Health and Human Development. Bldg 31, Room 2A32, MSC 2425, 31 Center Drive, Bethesda, MD 20892-2425. (800) 505-2742. 〈http://www.nichd.nih.gov/sids/sids.htm〉.
National SIDS Resource Center. 2070 Chain Bridge Road, Suite 450, Vienna, VA 22181. (703) 821-8955. 〈http://www.circsol.com/SIDS/〉.
Sudden Infant Death Syndrome
SUDDEN INFANT DEATH SYNDROME
Sudden infant death syndrome (SIDS) refers to the sudden unexpected death of an infant under the age of one year who prior to the event was considered to be completely healthy. The diagnosis also requires that a review of the clinical and environmental history, death scene investigation, and autopsy fail to reveal an alternative explanation of the death. In other words, the diagnosis of SIDS remains a diagnosis of exclusion.
SIDS remains the primary cause of death for infants between one month and six months of age. Prior to 1991 the incidence rates of SIDS in the United States ranged between 1.2 and 2 per 1,000 live births. Of the developed countries of the world, some, including Sweden, Hong Kong, and Japan, reported rates as low as 0.3 to 0.5 per 1,000 live births. Others, such as Australia (especially Tasmania), New Zealand, and Northern Ireland reported rates as high as 3-7 per 1,000 live births. In 1995, three years after the Academy of Pediatrics issued guidelines recommending placing infants in the nonprone position (i.e., not lying on the stomach) for sleeping, Michael Malloy and his colleagues published a study noting a 33 percent drop in the incidence of SIDS within the United States. Other countries reported similar experiences after adopting infant sleep position changes. This lowered incidence was maintained for succeeding years, but it remains to be seen if additional decreases will occur with increasing compliance with the recommended sleep positioning guidelines.
While the cause of SIDS remains elusive, multiple studies have documented consistent epidemiological factors associated with higher SIDS risks in some groups of infants. Risk factor categories include maternal and prenatal, neonatal (newborn), postneonatal, geographic, and race/ethnicity groupings.
Maternal and prenatal risk factors constitute a lengthy list of biological and environmental conditions. These include shorter interpregnancy interval, increased placental weight, low socioeconomic status, nutritional deficiency, anemia, urinary tract infection, intrauterine hypoxia (oxygen deficiency), fetal growth retardation, smoking, drug exposure, poor prenatal care, young age, lower education, and increased number of pregnancies. Several studies have identified maternal smoking as a significant risk factor. The National Institute of Child Health and Human Development (NICHD) conducted a large study in the United States of 757 SIDS cases with two matched control groups. Seventy percent of the SIDS mothers in this study smoked. When compared with the control groups, the risk for infants of mothers who smoked is doubled and progressively increases as the number of cigarettes smoked per day increases. These infants also die at younger ages. Constriction of blood vessels leading to chronically diminished oxygen delivery to fetal tissues is thought to be the mechanism by which smoking increases the risk of SIDS.
Neonatal risk factors include poor growth, asphyxia (inadequate oxygen delivery to body tissues), prematurity, and low birthweight. As the gestational age decreases, the relative risk of SIDS increases. This is also true of birthweight. The incidence of SIDS in preterm infants whose birthweight is greater than 1,500 grams (3 pounds, 5 ounces) is about 8 per 1,000 live births, compared to preterm infants with birth-weights less than 1,500 grams, where the risk rises to 10 per 1,000 live births. Postnatally, male sex, age (two to four months), bottle feeding, overheating, smoking exposure, soft bedding materials, no pacifier use, and prone sleeping position have been identified as significant factors that independently increase the risk of SIDS.
Geographic and race/ethnicity factors play an additional role in increasing the relative risks. SIDS rates increase during cold weather months, in economically poor countries, and in infants of black race or Native-American ethnicity. Worldwide, groups such as Gypsy, Maori, Hawaiian, and Filipino also have increased SIDS rates.
Extensive work has been done in an attempt to determine distinguishing pathological abnormalities that if present at autopsy would definitively identify SIDS as the cause of death. While there are findings that are commonly present at autopsy, no gross anatomical or microscopic abnormalities have been found that are distinct to SIDS. Nevertheless, a thorough postmortem (autopsy) examination demonstrating the absence of a causative abnormality is crucial to the diagnosis of SIDS. Especially important is not missing evidence of child abuse such as signs of (1) suffocation, (2) blunt trauma to the head, ribs, or extremities, and (3) retinal hemorrhages seen in shaken baby syndrome.
Commonly described findings in the central nervous system include: (1) increase in brain weight, presumably due to disordered development of the brain, (2) delayed myelination (maturation) of nerve cells, (3) gliosis (scarring) of brain-stem cells, (4) areas of leukomalacia (degeneration of brain tissue that occurred weeks to months earlier), and (5) abnormal dendritic spine density in selected areas of the brain stem. Evidence of chronic oxygen deprivation—such as persistence of brown fat around the adrenal glands, red blood cell production in the liver, and gliosis of the brain stem—add support to the theory that abnormal respiratory regulation may be the mechanism underlying SIDS.
Current thinking regarding the mechanism of SIDS is focused on disordered regulation of the cardiorespiratory systems. The primary area of physiological regulation in humans is within the brain stem, which is located anatomically at the base of the brain. Abnormal findings on autopsy (as described in the above section), combined with clinical observations of abnormal regulatory control, support the view that delayed maturation or disruption of brain stem function results in the infant's lack of ability to respond when breathing and circulation patterns are insufficient to maintain life.
Several areas of respiratory regulation have been studied. Abnormalities of breathing patterns—such as recurrent brief apneic episodes, prolonged apneic event, and periodic breathing—have been observed in infants who later died of SIDS. The ability to electronically monitor and record breathing patterns in infants sparked enthusiasm for screening and monitoring of infants felt to be at high risk for SIDS.
However, experience has proven this intervention is not reliable in detecting which infants with abnormal breathing patterns will actually subsequently die of SIDS. In addition, multiple false alarms from the monitoring equipment resulted in high noncompliance rates in the home setting.
Diminished respiratory responsiveness to excessive buildup of carbon dioxide (hypercarbia) or to excessively low levels of oxygen (hypoxia) has also been found in infants at risk for SIDS. Nevertheless, the ability to discriminate between these infants and those not at risk who may have similar diminished responsiveness is lacking as of 2001.
A third respiratory regulation control mechanism is the arousal response. When experiencing hypocarbia or hypoxia, a normal sleeping infant will arouse and increase respiratory efforts in response to this life-threatening situation. Infants lacking sufficient arousal responsiveness will continue sleeping, becoming progressively more hypoxic, resulting in cardiorespiratory failure and sudden death.
Other mechanisms that are thought to be associated with the occurrence of SIDS include abnormal cardiac rhythms and increased body and/or environmental temperatures. It is likely that the pathophysiology of SIDS involves complex interactions between abnormal regulatory control systems and epidemiological risk factors such as poor intrauterine growth, exposure to smoking, prone sleep positioning, and prematurity.
When a previously healthy infant is found unexpectedly dead, it is intensely emotionally traumatic. Caregivers blame themselves and each other. Families can be torn apart as a result of such an experience. For these reasons, proper management by experienced professionals is essential. A thorough investigation to determine the true cause of death is required. Other causes of sudden unexpected deaths of infants that have been mistakenly labeled as SIDS include congenital abnormalities of the heart and brain, metabolic disorders, occult infection (an infection that had escaped discovery), and accidental and non-accidental trauma. Nonaccidental trauma or child abuse mistaken for SIDS has been highlighted by several high-profile cases in both the United States and Europe. The recommended approach when an infant is found unexpectedly dead consists of a thorough investigation at the scene to detail the environmental circumstances. This should be followed by a careful review of the infant's medical, social, and family histories, followed by a complete postmortem examination by an experienced forensic pathologist. In some cases, laboratory studies on family members may be indicated. Counseling of parents is essential so that they have accurate information as to the cause of their infant's death and the implications for future children, as well as for emotional support. Community resources should be provided for ongoing support.
Although a definitive cause of SIDS remains unknown and there are no methods to predict which infants will die from SIDS, parents should be educated about strategies that will lessen the likelihood of a SIDS event. Parents should be advised to place infants on their backs for sleeping, provide a firm mattress, avoid loose clothing and blankets in the crib, avoid overheating their infant, breast-feed, and take their infant for regular medical care.
American Academy of Pediatrics. "Changing Concepts of Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position." Pediatrics 105 (2000):650-656.
American Academy of Pediatrics. "Distinguishing Sudden Infant Death Syndrome from Child Abuse Fatalities." Pediatrics 107 (2001):437-441.
Back to Sleep Campaign. "Reduce the Risk of Sudden Infant Death Syndrome (SIDS)" (brochure). Washington, DC: Back to Sleep Campaign, 1994.
Butlerys, Marc G., Sander Greenland, and Jess Kraus. "Chronic Fetal Hypoxia and Sudden Infant Death Syndrome: Interaction between Maternal Smoking and Low Hematocrit during Pregnancy." Pediatrics 86 (1990):535-540.
Hunt, Carl E., guest ed. "Apnea and SIDS" (special issue). Clinics in Perinatology 19, no. 4 (1992).
Hunt, Carl E. "Sudden Infant Death Syndrome." In Waldo E. Nelson ed., Nelson Textbook of Pediatrics. Philadelphia: Saunders, 1996.
Jeffery, Heather, Angelique Megevand, and Megan Page. "Why the Prone Position Is a Risk Factor for Sudden Infant Death Syndrome." Pediatrics 104 (1999):263-269.
Klonoff-Cohen, Hillary S., Sharon L. Edelstein, Ellen Lefkowitz, Indu P. Srinivasan, and David Kaegi. "The Effect of Passive Smoking and Tobacco Exposure through Breast Milk on Sudden Infant Death Syndrome." Journal of the American Medical Association 273 (1995):795-798.
Malloy, Michael H., and Daniel H. Freeman. "Birth Weight and Gestational Age-Specific Sudden Infant Death Syndrome Mortality: United States, 1991 versus 1995." Pediatrics 105 (2000):1227-1231.
Sudden Infant Death Syndrome
Sudden Infant Death Syndrome
Sudden Infant Death Syndrome (also known as SIDS) refers to the sudden death of an apparently healthy infant under 1 year of age whose death cannot be explained even after a complete investigation.
for searching the Internet and other reference sources
Mrs. Wyatt is doing all the things her doctor told her to do with her new baby. She puts him to sleep for naps and at night on his back instead of on his stomach. She makes sure the crib has a mattress that is firm, and that there are no blankets, pillows, or toys around the baby. She refrains from bundling her baby in thick clothing before putting the baby to bed.
The doctor recommended these things because they reduce the risk of Sudden Infant Death Syndrome (SIDS), a mysterious disorder that is a leading cause of death for children between the age of 1 month and 1 year.
SIDS kills more than 3,000 babies a year in America, usually while they are asleep in cribs. But since mothers like Mrs. Wyatt started to put their babies to sleep on their backs, and to adopt other preventive strategies, the number of SIDS deaths has dropped more than 40 percent.
No one knows for sure why these babies die. Most of the babies appear to be healthy until their deaths.
Parents often feel guilt mixed with their grief over the death. They think perhaps there was something they could have done. But SIDS is no one’s fault.
Researchers have not discovered a cause for Sudden Infant Death Syndrome in the more than 30 years they have been studying it. In fact, it is easier to say what SIDS is not than what it is. SIDS does not result from suffocation, choking, vomiting, or a fatal reaction to a vaccination*. A baby does not catch it like a cold.
- * vaccination
- (vak-si-NAY-shun) is taking into the body a killed or weakened germ, or a protein made from such a microbe, in order to prevent lessen, or treat a disease.
The only time doctors say that a baby has died of SIDS is if no other cause of death is found after there has been an autopsy*, an investigation of the place where the baby died, and a review of the baby’s medical history.
- * autopsy
- (AW-top-see) is the examination of a body after a person has died, to determine the cause of death.
The Back to Sleep Campaign
For decades, parents thought it was best to put babies to sleep on their stomachs. They thought that if babies were on their backs, they would choke on their vomit if they threw up.
Doctors today say that should not be a concern. In fact, a national Backto Sleep Campaign was launched in 1994 by the U.S. National Institute of Child Health and Human Development (NICHD) and other organizations to inform parents that they should put healthy babies to sleep on their backs, because doing this appears to reduce the risk of SIDS.
It was in 1992 that the American Academy of Pediatrics first recommended that babies sleep on their backs. Between 1992 and 1997, the number of children sleeping on their stomachs dropped from 70 percent to 21 percent, and the death rate from SIDS dropped by 42 percent.
The Back to Sleep campaign also informed health professionals and the general public about other ways to lower the risk of SIDS. These include:
Having the mother avoid smoking during pregnancy
Making sure the mother gets medical care during pregnancy
Having family members avoid smoking around the baby after it is born
Making sure the baby gets ongoing medical care after it is born
Having the mother breast-feed the baby
Providing the baby with a firm mattress
Keeping pillows, blankets, and toys in the crib from crowding the baby
Not dressing a baby in too many clothes when the baby is sleeping.
Not all babies should sleep on their backs. A few have problems with their airways or keeping food down. Doctors may recommend in these rare cases that the babies be placed on their stomachs on a firm mattress without soft pillows, blankets, or plush toys.
Some parents have misunderstood the intent of the Back to Sleep Campaign. They never put their children on their stomachs, even when they are awake. Doctors say it is important for children’s physical and mental development to spend some time on their stomachs while they are awake, so long as an adult is watching.
Recent research suggests that infants who die of SIDS might have a problem in an area of the brain that controls two functions while they are asleep: breathing and waking up. This problem area in the brain, however, might not be enough on its own to cause SIDS. Other things may have to happen to reduce the amount of oxygen a baby gets, or to disrupt the baby’s breathing and heart rate.
For example, babies might not get enough oxygen when they breathe air that is trapped in soft beds or in folds of blankets near their mouths. This is not the same as suffocation, which usually involves completely blocking a person’s ability to take in air. In SIDS, the babies may be getting air but not enough oxygen, because they are breathing in their own exhaled breath.
Respiratory infections such as a cold or other ailment also can make breathing difficult for a baby.
Usually, babies would wake up and cry if they were not breathing well. But it may be that some babies cannot process the signals in the brain when they are not breathing properly.
These examples could help explain why babies who sleep on their stomachs or have infections are at higher risk of SIDS. It also might explain why SIDS is more likely to occur in the winter, when the risk of infection is higher and babies might be sleeping with more bedclothes or blankets.
Researchers are investigating other possible physical problems that could contribute to the risk of SIDS. One possible factor is an immune system* disorder that creates too many white blood cells and proteins, which disrupt the brain’s control over breathing and heart rate.
- * immune system
- is the system that protects the body from diseases. It includes elements such as the thymus, spleen, lymph nodes, bone marrow, and antibodies (AN-te-bod-eez).
Like many disorders, SIDS might have a combination of factors that cause it, including some that have not been discovered.
Although research is beginning to suggest causes for SIDS, there is still no way to predict who will die of the disorder. The vast majority of babies who are laid to sleep on their stomachs, have infections, or sleep with blankets do not die from SIDS. Others who sleep on their backs in ideal conditions still die of the disorder.
There are no warning signs of SIDS before a baby dies. Doctors only diagnose it after ruling out other possible causes of death.
Certain things are known. SIDS can happen any time within the first year, but it occurs most often between the first and fourth month after birth. Seldom does it occur within the first 2 weeks following birth or after 6 months.
A baby is more likely to die of SIDS if the baby has:
- A mother who smoked during pregnancy
- A mother less than 20 years old
- A mother who did not receive proper medical care before her baby was born
- A birth before the full 9 months of a normal pregnancy
- A lower than normal birth weight
- Family members who smoked around the baby.
However, babies who are breast-fed have a lower risk of SIDS than babies who are fed with a bottle. One possible reason might be because breast-feeding helps reduce the risk of the types of infections that may contribute to breathing problems.
Horchler, Joani Nelson, and Robin Rice Morris. The SIDS Survival Guide: Information and Comfort for Grieving Family and Friends and Professionals Who Seek to Help Them. Revised and updated edition. Hyattsville, MD: SIDS Educational Services, 1997.
Guntheroth, Warren G. Crib Death: The Sudden Infant Death Syndrome. Third edition. Armonk, NY: Futura Publishing Company, Inc., 1993.
The National Institute of Child Health and Human Development (NICHD), part of the U.S. National Institutes of Health (NIH), posts information about SIDS on its website, which also includes information on the Back to Sleep Campaign. Telephone 800-505-2742 http://188.8.131.52/publications/pubs/sidsfact.htm http://www.nichd.nih.gov/sids/sids.htm
Sudden Infant Death Syndrome Network, P.O. Box 520, Ledyard, CT 06339. This organization is dedicated to providing information on SIDS, and support for families who lose a baby. It features information in more than a dozen languages, http://sids-network.org
National SIDS Resource Center, 2070 Chain Bridge Road, Suite 450, Vienna, VA 22182. Telephone 703-821-8955 http://www.circsol.com/SIDS
Sudden Infant Death Syndrome (SIDS)
Sudden Infant Death Syndrome (SIDS)
Sudden Infant Death Syndrome (SIDS) was first defined in 1969 as "The sudden death of any infant or young child, which is unexpected by history, and in which a thorough post mortem examination fails to demonstrate an adequate cause for death" (Beckwith 1970, p. 18). New definitions have since been suggested, but they have not been internationally accepted (Guntheroth 1995; Byard 2001). The definition of SIDS has served to focus the attention of the world upon a largely unrecognized problem, to stimulate scientific research, and to increase support for the victims' families.
Current Knowledge of SIDS
It has been suggested that SIDS victims have some inherent weakness due to fetal influences or genetic make-up, which may only become obvious when he or she is subjected to stress during a vulnerable developmental period (Rognum 1995). Many consider SIDS to be due to many factors, not a specific disease process, but a lethal situation in which an infant succumbs from the additive effects of several factors (Byard 2001).
SIDS is an entity with no pathological findings at autopsy, that is, a diagnosis by exclusion. A few similarities are often found at autopsy, but these findings do not provide an explanation for death (Guntheroth 1995; Byard 2001). Externally, the infant appears well developed, and all the pathologist may find is a small amount of mucoid, watery, or bloody fluid in the nostrils. Internally, minute hemorrhagic spots (petecchiae) are seen on the surface of the thymus, lungs, and heart in approximately 75 percent of the cases. There is often evidence of a slight infection in the upper airways, as well as increased amounts of fluid (congestion and edema) and numerous cells (macrophages) in the air sacks of the lungs. Several conditions involving all organ systems may be responsible for sudden death in infants and small children that appear reasonably well prior to death. In investigating cases of suspected SIDS, the possibility of underlying illness, accident, or even homicide must be considered. If an adequate postmortem examination, including a review of the history and circumstances is not performed, the possibility of determining other causes of death may be lost.
In the 1990s, researchers have focused on the role of the immune system in SIDS. Many SIDS victims have shown signs of a slight infection prior to death, and there is often evidence of a subacute infection in the upper airways, or a slight cold. This has led to several studies of the involvement of infections and regulatory immune mechanisms in SIDS. The immune system undergoes rapid development during the first weeks and months of life and can trigger a reduction of oxygen to the blood (hypoxemia), resulting in a self-amplifying vicious circle that can result in death. A possible biochemical marker for hypoxic (insufficient oxygen reaching the infant) episodes prior to death from SIDS, hypoxanthine, has previously been identified (Rognum 1995).
The pathophysiology of SIDS remains unknown. Several studies have suggested possible abnormalities, such as respiratory pattern, arousal responses, temperature regulation, cardiac control, and autonomic function. Abnormalities in the way the nervous system regulates cardiorespiratory control or other autonomic functions provide perhaps the most compelling hypothesis (Hauck 2000).
Epidemiological research has shown modifiable and nonmodifiable factors to be associated with increased or decreased SIDS risk (Guntheroth 1995; Rognum 1995; Byard 2001). From the middle of the 1980s, several studies began to report an increased risk of SIDS attributed to prone sleeping (sleeping on the stomach). Back to sleep campaigns were launched in several countries, including Australia, the United States, Germany, France, and Italy, resulting in an immediate decrease in the SIDS rate. Prone sleeping is still a major risk factor for SIDS, as is side sleeping. Other sleep environment factors, such as soft bedding and the use of pillows, covering of the head or face, the use of duvets, and overheating, have also, alone or together with prone sleeping, been associated with increased risk of SIDS. At the beginning of the 1990s there was an increase reported in the risk of SIDS associated with bedsharing or co-sleeping with an adult. Such an association is still controversial.
Sociodemographic factors, such as lower socioeconomic status (measured by low income, unemployment, low education, and young maternal age) have consistently been shown to be associated with greater risk of SIDS. Risk differences are found among different races, with African Americans and indigenous populations in the United States, Australia, and New Zealand having the highest rates, and most Asian communities around the world the lowest. An age peak has been seen between two to four months of age; more males than females are affected;, and SIDS has been more common during the colder months of the year. Factors related to pregnancy have been shown to increase the risk of SIDS, such as higher birth order, lower birth weight, and short gestation period. Maternal smoking during pregnancy is consistently associated with risk of SIDS, often showing a dose-response effect; that is, the more a mother smokes, the greater the risk of SIDS for her infant. Smoking is perhaps the most important maternal risk factor and is viewed as the most important modifiable risk factor of SIDS altogether, after the reduction in prone sleeping. The use of illegal drugs is associated with a somewhat increased risk.
Several epidemiological studies into possible risk and/or protective factors of SIDS have concluded that pacifier use may protect against SIDS. As to the role of breastfeeding as a potential preventive measure against SIDS, studies have been inconclusive. At the end of the 1990s however, comparison of epidemiological characteristics before and after the decline in SIDS rate due to "back-to-sleep" campaigns disclosed significant changes in variables such as a reduction in the two to four month age peak and in the winter peak as well as increased risk with young maternal age, low socioeconomic status, and maternal smoking during pregnancy (Byard 2001). Understanding these changes, coupled with the effects of reducing modifiable factors, will probably reduce the SIDS rate further, and, it is hoped, eventually lead to an understanding of both the etiology and pathogenesis of SIDS.
Genetic factors have also been thought to play a role in SIDS with findings of a modest, but significantly increased, recurrence rate of SIDS in families (Guntheroth 1995; Hauck 2000; Byard 2001). Death from inherited metabolic disorders has been proposed as the cause of death in a small number of SIDS cases. The long-QT syndrome, a cardiac arrhythmia that can cause sudden death, is another inherited disorder proposed as the cause of death in some cases of SIDS.
How SIDS Affects the Family
Suddenness of a loss is particularly stressful to survivors and may lead to long-lasting family crisis. The suddenness of the death of an apparently well infant leaves the family with no opportunity to gradually accept the loss (Guntheroth 1995). Studies have shown that grief in SIDS decreases over time, but a considerable number of parents are still actively dealing with the loss throughout the first year. Men and women grieve differently, and the loss can have an effect on the marriage; some are strengthened, and some end in divorce. Other family members and siblings are affected by the loss. According to SIDS parents, their lives are never the same, and this may be reflected through changes in educational or vocational paths. Many have gotten involved in local, national, or international SIDS organizations in an effort to bring support to recently bereaved families and to promote education and awareness of SIDS to the general public. When a loss such as SIDS occurs, the bereaved frequently search for meaning in the event and for the cause. And in pursuit of the cause, self-accusation is frequent. Although research results can, for some, increase this feeling of guilt, most enthusiastically support research through personal donations or fundraising efforts. It is a way to keep the memory alive and to help find an answer to the SIDS enigma (Byard 2001).
beckwith, j. b. (1970). "discussion of terminology and definition of the sudden infant death syndrome." in sudden infant death dyndrome. proceedings of the second international conference on the causes of sudden death in infants, ed. a. b. bergman, j. b. beckwith, and c. g. ray. seattle: university of washington press.
byard, r. w., and krous, h. f. (2001). sudden infantdeath syndrome: problems, progress and possibilities. london: arnold.
hauck, f. r., and hunt, c. e. (2000). "sudden infant death syndrome in 2000." current problems in pediatrics 30(8):237–261.
guntheroth, w. g. (1995). crib death: the sudden infantdeath syndrome. 3rd edition. armonk, ny: futura publishing.
rognum, t. o. (1995). sudden infant death syndrome.new trends in the nineties. oslo: scandinavian university press.
sids international. available from http://www. sidsinternational.minerva.com.au.
Sudden Infant Death Syndrome
SUDDEN INFANT DEATH SYNDROME
Sudden infant death syndrome (SIDS) is the unexplained death of an apparently healthy infant, usually during sleep. The condition is also known as crib death.
Sudden infant death syndrome strikes 1 to 2 infants in every 1,000. It is the leading cause of death in newborn children. SIDS accounts for about 10 percent of deaths occurring during the first year of life.
SIDS most commonly strikes babies between the ages of two and six months. It almost never occurs in babies younger than two weeks or older than eight months. Most SIDS deaths occur between midnight and 8 a.m.
More than 4,800 babies died of SIDS in 1992. That number dropped to 3,279 deaths in 1995. One reason for this decrease was better education about the disorder. Parents were being taught to place babies on their backs or sides when put to bed, which is thought to reduce the risk of SIDS. In spite of this progress, doctors still have not determined the cause of SIDS.
While the exact cause or causes of SIDS are still unknown, one important factor may be infection of the respiratory (breathing) tract. Some studies show that many babies who die of SIDS had recently been treated for a cold or other respiratory illness. Most SIDS deaths occur during the winter and early spring. These seasons are the peak times for respiratory infections. Research suggests that the following factors may increase the risk of SIDS for a baby:
- The baby sleeps on his or her stomach.
- The baby's mother smoked during pregnancy.
- The mother was under the age of twenty at pregnancy.
- The mother abuses drugs.
- The mother received little or no prenatal (before birth) care.
- The baby was born prematurely (early) or with a low birth weight.
- The baby lives in house where someone smokes.
- The baby is male (SIDS is more common for infant boys that girls).
- Baby is a member of a minority or low-income family.
- Baby's family has a history of Sudden Infant Death Syndrome.
Sudden Infant Death Syndrome: Words to Know
- A medical examination of a dead body.
- Crib death:
- Another name for sudden infant death syndrome.
- Secondhand Smoke:
- One person's exhaled cigarette smoke that is breathed in by another person nearby.
Theories about SIDS
Researchers have long been puzzled as to the actual cause of SIDS. While there are a number of theories to explain the condition, none of them have been proven. Doctors are often unable even to determine whether a baby died because of a heart problem or because it suddenly lost the ability to breathe.
Generally the theories focus on either medical disorders or the baby's physical surroundings.
MEDICAL DISORDERS. One theory about the cause of SIDS is that the baby's upper airway gets blocked. The baby suffocates because it can not get oxygen. Another theory is that the baby's blood has the wrong composition and may not contain enough of certain chemicals needed to keep the brain functioning.
A third theory is that SIDS babies have a faulty nervous system. Normally, infants have a mechanism that wakes them up when their oxygen supply is low. It could be that SIDS babies don't have that mechanism. Other theories blame SIDS on a faulty immune system or the buildup of certain chemicals called fatty acids in the baby's blood.
PHYSICAL SURROUNDINGS. Some researchers think SIDS may be caused by the way a baby sleeps. For example, it may be that a baby sleeps with its face in soft bedding or that the baby may be wrapped too tightly in blankets. Either of these situations can stop the baby from breathing properly or getting enough oxygen.
SIDS does not have any warning symptoms. Death occurs suddenly and unexpectedly.
The diagnosis of SIDS is usually a diagnosis of exclusion. That means that all other possible causes of death are first ruled out. If no other cause of death can be found, then SIDS may be diagnosed.
TEN LEADING CAUSES OF INFANT DEATH (U.S.)
Sudden Infant Death Syndrome (SIDS)
Respiratory Distress Syndrome
Problems related to complications of pregnancy
Complications of placenta, cord, and membrane
Intrauterine hypoxia and birth asphyxia
Source: Monthly vital Statistical Report, 46, no. 1, Supplement, 1996. (Reproduced by permission of Stanley Publishing)
Certain diagnosis of SIDS can be made only with an autopsy. An autopsy is a medical examination of a dead body. In about 20 percent of all SIDS cases, an autopsy shows a specific cause for death, such as suffocation. Parents sometimes reject the idea of having an autopsy on their baby, but the procedure can help explain how the baby died. Knowing the actual cause of death can help parents understand that the baby's death was no fault of their own.
There is no treatment for SIDS. The best that can be done is to take action to prevent babies from dying of the condition. A baby's parents may, however, benefit from treatment including counseling and support from groups of other SIDS parents.
At least some cases of sudden infant death syndrome can be prevented. Parents can take a number of actions that will reduce the risk of SIDS for their babies. These actions include the following:
- Sleep position. At one time, parents were taught to put their babies on their stomachs when they went to bed. That position was thought to prevent the baby from choking in its sleep. Experts now suggest that babies sleep on their backs or their sides. In these positions, they are less likely to have their faces covered in pillows and blankets.
- Good prenatal care. Women should get the best possible medical care while they are pregnant. This care will ensure that they are themselves healthy. Expectant mothers should be warned about the risks of smoking, alcohol intake, and drug use. A healthy mother's body is the best protection the newborn baby can have. Good prenatal care also involves education for the mother. She should be taught the best techniques for caring for her new baby.
- Proper bedding. Soft bedding, such as beanbags, waterbeds, and soft mattresses, increase the risk for SIDS. Babies should sleep on firm mattresses with no soft or fluffy materials near by. Soft stuffed toys should not be placed in a crib while the baby sleeps.
- Room temperature. A baby's room should be kept at a temperature that is comfortable for the parents. A baby who becomes too warm may sleep too deeply and may find it more difficult to wake up if it has trouble breathing.
- Diet. Some studies show that babies who are breast-fed are at lower risk for SIDS. Mother's milk may provide additional protection against infections that can cause SIDS in infants.
- Bed sharing with parents. Opinions differ as to whether bed sharing between mother and baby increases or decreases the risk of SIDS. Bed sharing may encourage breast-feeding, which decreases the risk of SIDS. Parents who bed share may also be more aware of any problems their baby has breathing. On the other hand, some studies show that bed-sharing increases the risk of SIDS. In any case, parents should remember cautions about the use of bedding if their babies sleep with them. They should also remember that an adult's bed does not have the same safety features of an infant's crib.
- Secondhand smoke. The baby's room should be kept free of tobacco smoke at all times.
- Electronic monitoring. Electronic devices are now available that allow parents to listen in while their baby is sleeping. These devices sound an alarm if the baby stops breathing. So far, however, there is no scientific evidence that electronic devices reduce the risk of SIDS. The U.S. National Institutes of Health recommends their use only for babies known to be at risk for SIDS. These babies include premature infants, infants who have had previous breathing problems, or infants with siblings who have died of SIDS.
FOR MORE INFORMATION
Horchler, Joan Nelson, and Robin Rice Morris. The SIDS Survival Guide: Information and Comfort for Grieving Family and Friends and Professionals Who Seek to Help Them. Hyattsville, MD: SIDS Educational Services, 1997.
Sears, William. SIDS: A Parent's Guide to Understanding and Preventing Sudden Infant Death Syndrome. Boston: Little Brown & Company, 1996.
Association of SIDS and Infant Mortality Programs. 630 West Fayette Street, Room 5–684, Baltimore, MD 21201. (410) 706–5062.
National Institute of Child Health and Development/Back to Sleep. 31 Center Drive, MSC2425, Room 2A32, Bethesda, MD 20892–2425. (800) 505–CRIB. http://www.nih.gov/nichd.
National SIDS Resource Center. 2070 Chain Bridge Road, Suite 450, Vienna, VA 22181. (703) 821–8955.
IDS Alliance. 1314 Bedford Avenue, Suite 210, Baltimore, MD 21208. (800) 221–7437.
Child Secure. [Online] http://www.childsecure.com (accessed on November 4, 1999).
Sudden Infant Death Syndrome (SIDS)
Sudden infant death syndrome (SIDS)
Sudden infant death syndrome (SIDS) is the term used to describe the sudden and unexplained death of an apparently healthy infant. This unpredictable and unpreventable phenomenon is the leading cause of death in babies less than one year old and strikes infants of all ethnic or economic backgrounds. Several theories exist but none can fully explain it or stop it from happening.
SIDS in history
The sudden death of a baby while sleeping, although tragic, is nothing new. It has a history of at least 2,000 years and is even mentioned in the Bible. In First Kings, the story is told of how King Solomon judged who was the real mother of a surviving child. The child's dead sibling was thought to have "died in the night because she overlaid it." "Overlaying" or the accidental suffocation of an infant by an adult who rolled on the baby while sleeping was for centuries thought to be the only reasonable explanation for an apparently healthy infant going peacefully to sleep and never waking up. In ancient Egypt, a mother who was judged to be responsible for doing this was sentenced to hold the dead infant for three days and nights. The first known medical textbook written during the second century a.d. by Greek physician Soranus of Ephesus instructs mothers and wet-nurses (female servants who were nursing or breast feeding their own child and who also would nurse the baby of their mistress or employer) never to sleep with infants in case they should accidentally fall asleep on the baby and somehow suffocate it.
References to "overlaying" are known to exist throughout the centuries, and it appears again and again in church records and doctors' records. It is even found in records from the Plymouth colony in New England where it was called "stifling." The question of whether a baby had been killed deliberately by an adult was always in the background, and often authorities would have to judge the fate of parents whose healthy infant died suddenly and therefore suspiciously.
Nineteenth-century doctors naturally tried to explain scientifically these sudden deaths of babies, and one of the first such explanations was that the infant suffered from some sort of respiratory ailment. By the beginning of the twentieth century, sleep apnea (pronounced AP-nee-uh), in which a baby stops breathing for some reason but does not start up again, was considered a cause. By the 1930s, the role of infection was being considered, and by the 1940s, most American mothers were no longer taking their children to bed with them for fear of accidentally smothering them.
Words to Know
Apnea: Cessation of breathing.
Hypoxia: A deficiency of oxygen reaching the tissues of the body.
The first modern study of any and all of the factors that might be involved in a case of sudden infant death was done in 1956. By the late 1950s, many thought that such death was caused by some sort of abnormal function of the baby's breathing reflex. During the 1960s, many new theories were offered, such as a hypersensitivity to milk, an abnormal heartbeat, or some form of hypoxia (pronounced hi-POCKS-ee-uh), which is a lack of oxygen. In 1963, the first international conference on sudden infant death was held in Seattle, Washington, which produced not only more theories but also increased awareness on the part of the public. It was at the second international conference that a definition was agreed upon and the condition came to be named SIDS. The definition also stressed that all possible known causes must have been ruled out by an autopsy, a death scene investigation, and a careful review
|TEN LEADING CAUSES OF INFANT DEATH (U.S.)|
|Source: Monthly Vital Statistical Report, 46, no. 1 Supplement, 1996.|
|Sudden Infant Death Syndrome (SIDS)|
|Respiratory Distress Syndrome|
|Problems related to complications of pregnancy|
|Complications of placenta, cord, and membrane|
|Intrauterine hypoxia and birth asphyxia|
of the medical history. These guidelines are still followed today. During 1972, the issue of SIDS received even more attention as the United States Congress held hearings on the subject and increased funding for research.
Despite this history and attention, it is nonetheless still true that in the U.S., more children die of SIDS in one year than die of cancer, leukemia, heart disease, cystic fibrosis, and child abuse combined. SIDS is, therefore, the leading killer of children between one week and one year of age. What physicians know about SIDS is more of a description than a real understanding. They know that it occurs to infants up to one year old, but most often between the ages of two and four months. It occurs during sleep and strikes without warning. It may occur a few minutes after a baby is put down for the night or after sleeping all night. It has even happened to a sleeping baby in a parent's arms. It affects all types of children in all types of families, and has no relation to ethnicity or income level. However, for some reason, African-American infants die of it twice as often as white infants. Males babies are 50 percent more likely to die of SIDS than females, but neither parents nor doctors can tell which babies will die.
Although no specific cause is yet known, researchers have put together a typical case of what does happen when SIDS strikes. They now believe that certain babies are more at risk than others, and that babies born with one or more conditions can make them especially vulnerable to the normal stresses that all babies experience. Some of these risk factors are stress caused by infection, a birth defect, or a failure to develop. Other factors that are believed to increase vulnerability are premature birth, low birth weight, a sibling who died of SIDS, or babies who have a twin. Other external factors that seem to matter include cigarette smoking or drug use by the mother during pregnancy as well as other medical complications she may have experienced while pregnant. Finally, statistics show that babies who are breast-fed are less likely to die suddenly than those who were bottle fed. The very number of these factors points out how little modern science knows about this syndrome.
Search for a cause
As to what causes SIDS, two major theories best exemplify the hundreds of theories already proposed. One of these says that SIDS happens to normal, healthy babies who have something go wrong with them because of the fact that they are developing so rapidly. This notion of SIDS as a developmental phenomenon argues that because a baby's brain is growing so quickly during its first six months, there is the possibility that it may send an abnormal or wrong message to a critical organ system. For example, it might tell the throat to "close off" instead of "open up" after a breath. The other major theory says that babies who die from SIDS were basically not healthy infants, and that some condition predisposed them to it. This idea says that the baby's developmental experience in the womb before it was born may have made it more at risk. Like the other theory, this theory also focuses on the brain, but argues that it is significant that many SIDS victims have subtle or minor brain abnormalities in the part of the brain that affects sleep.
Over a long period of time, the number of SIDS deaths has tended to remain roughly the same (about 4,000 a year), although starting in 1993 the rate of SIDS decreased some 30 percent. This is thought to be the result of a 1992 effort to educate parents to the fact that infants who sleep
on the stomachs are more at risk than those who sleep on their backs. It is now standard practice for doctors to tell new parents that normal babies should sleep face up during the first six months of life.
The death of any child is a terrible thing, but when it occurs with such suddenness and with no forewarning, it can be devastating to the survivors. Often, parents cannot rid themselves of guilt feelings that somehow they were to blame or that they could have done something to prevent it. Fortunately, there are many support groups available for both parents and siblings of a SIDS victim, many of whom feel so bad they become psychological victims themselves. With all the attention and research that SIDS is attracting, the rate of the syndrome may be falling. However, because SIDS is still so unpredictable, researchers must continue their work to seek a cause. Many believe that when SIDS is finally understood, it will have more than one simple explanation.
Sudden Infant Death Syndrome
Sudden Infant Death Syndrome
Sudden infant death syndrome (SIDS, also known as crib death) is the unexpected death of an infant for which postmortem examination fails to find adequate cause. It has a long history and has been explained, at various times, as infanticide, overlaying (accidental suffocation in a family bed), and thymus death, or status lymphaticus. The reasons why infants died suddenly were often obscure. In 1855 Thomas Wakley, the founder and editor of the Lancet, wrote about "infants found dead in bed," and there has been a stream of publications on the subject ever since. During the nineteenth century, the frequency of infanticide was a matter of growing concern. In the mid-1860s over 80 percent of all coroners' reports of murder in England and Wales involved infants. Disraeli said that infanticide was "hardly less prevalent in England than on the banks of the Ganges." The subject excited considerable interest in British newspapers and medical journals from the 1860s onwards. Death from overlaying was also common, perhaps because of overcrowding and the prevalence of drunkenness.
The unexpected death of an infant without obvious cause was long thought to be due to an enlarged thymus. This was a misunderstanding, but it lasted until modern times. Normal infants have large thymus glands, but most infant deaths occurred after prolonged illness had depleted the thymus so that postmortem examinations revealed small thymuses. A child who died suddenly was likely to have a normal, large thymus, and this was taken to be the cause of death. A disease, status lymphaticus, was invented to legitimize it. During the early twentieth century this disease caused considerable interest and anxiety. It was later questioned and eventually shown to be nonexistent.
Yet infants continued to die unexpectedly. During the 1940s the concept of crib death (also called cot death ) became prominent and gradually the label changed to sudden infant death syndrome. Most experts in the field agree that it has many possible causes. These include infection (often sudden pneumonia), hyperthermia (overheating due to too hot a room or too many bedcoverings), murder, and unintentional poisoning (perhaps from cigarette smoke or chemicals, possibly arsenic, phosphorus, and antimony in crib mattresses, perhaps from obscure fungi that grow in old mattresses). The possible involvement of mattresses has led to accusations of cover-ups by governments and manufacturers. Increasing publicity has promoted the adoption of baby monitors, which record a baby's breathing and sound an alarm if the infant ceases to breathe.
The current consensus of opinion is that crib death appears to be an abnormal response to everyday challenges and stresses that do not affect most babies. After (or coincidental with) new regulations about crib mattresses and public advice to put babies into their cribs on their backs rather than on their stomachs, the incidence of SIDS fell by two-thirds, but it is still the largest single killer of babies under one year and the subject is of considerable interest to both pediatricians and the public. The Foundation for the Study of Infant Deaths initiates research and also campaigns for greater compassion to be shown by health professionals to bereaved parents.
See also: Infant Mortality; Pediatrics.
Bergman, Abraham B., J. Bruce Beckwith, and C. George Ray, eds. 1970. Sudden Infant Death Syndrome: Proceedings. Seattle: University of Washington Press.
Golding, J. 1989. "The Epidemiology and Sociology of the Sudden Infant Death Syndrome." In Paediatric Forensic Medicine and Pathology, ed. J. K. Mason. London: Chapman and Hall Medical.
Sudden Infant Death Syndrome
SUDDEN INFANT DEATH SYNDROME
SUDDEN INFANT DEATH SYNDROME (SIDS), sometimes referred to as crib death, is a medical term for the decease of an apparently well infant. It describes a death that remains unexplained after all known and possible causes have been ruled out through autopsy, investigation of the scene, and review of the child's medical history. SIDS was first identified as a separate medical entity and named in 1969. SIDS causes the death of as many as 7,000 infants each year in the United States. It is the most common cause of death in children between their first month and first year of age. SIDS more frequently affects males than females and nonwhites than whites. It affects infants born into poverty more often than those in higher-income situations. Most at risk are infants born to women with inadequate prenatal care, infants born prematurely, and infants whose mothers smoked during pregnancy or after delivery. Deaths usually occur during sleep, are more likely during cold months, and occur more frequently in infants who sleep on their stomachs than in infants who sleep on their backs.
In 1994 a "Back to Sleep" campaign encouraging parents and caretakers to put babies to sleep on their backs was initiated as a cooperative effort of the U.S. Public Health Service, the American Academy of Pediatrics, the SIDS Alliance, and the Association of SIDS and Infant Mortality Programs. The cause of SIDS is unknown. Theories include an unidentified birth defect, stress in a normal baby caused by infection or other factors, and failure to develop. Because no definitive cause can be found and because parents are totally unprepared for such a loss, the death often causes intense feelings of guilt.
Guntheroth, Warren G. Crib Death: The Sudden Infant Death Syndrome. Armonk, N.Y.: Futura Publishing, 1995.