It is one of the greatest tragedies that can befall parents – walking into an infant’s bedroom to find that their child has died – suddenly, unexpectedly, and without explanation.

Sudden Infant Death Syndrome (SIDS) has perplexed parents, physicians and scientists alike for decades. SIDS is a diagnosis of exclusion – doctors diagnose a child with SIDS when the cause of death remains unexplained after an investigation including an autopsy, an examination of the death scene, and a review of the child’s medical history and symptoms.

Facts & Risk Factors

Though the cause of SIDS, a syndrome which affects approximately 2,500 children each year, is not yet determined, some facts are known. SIDS occurs in children up to one year of age, but most cases occur between 2 and 4 months of age. Male babies are more likely to be diagnosed with SIDS, and more cases occur in the winter months. Beyond these few facts, researchers and physicians have been left with the challenge of putting the pieces of the puzzle together.

In the process of trying to understand SIDS, research has led to the identification of a number of risk factors which tend to appear commonly in SIDS cases.

Children who might be at risk for SIDS are:

* Sleeping in the prone position (stomach sleeping)

* Sleeping on beds that are unsafe (couches, daybeds, waterbeds, etc.)

* born to mothers who smoke during pregnancy

* exposed to secondhand smoke

* born to mothers under 20 years of age

* premature or have a low birthweight

* born to mothers with late or no prenatal care

* recovering or have recovered from respiratory or intestinal infections

Despite the fact that these risk factors can be identified, many parents are still left feeling unsure about what they can do to protect their children from SIDS.

Precautionary Measures

Researchers have learned that an infant’s sleeping environment can be hazardous if precautions aren’t taken. It is important for babies to sleep on a firm mattress or firm sleeping surface that does not contain fluffy blankets, pillows, comforters or toys in the sleeping area. The baby’s face and head should always be uncovered during sleep, and the child should be put to sleep on his or her back. The temperature in the bedroom is also very important – many parents believe that rooms need to be heated much warmer for their children, but in fact rooms should be kept at temperatures that are comfortable for adults. High room and body temperatures have been found in SIDS cases, and this might explain why there is a greater incidence of SIDS in the winter when parents are more likely to overheat their children’s bedrooms or compensate for the cold with extra blankets and clothing.

Mothers can also take steps to reduce their children’s risk of SIDS by ensuring that they maintain healthy lifestyles. It is very important for women to receive adequate prenatal care and have frequent check-ups. Additionally, whenever possible, mothers should try to breast feed their children. Though formula feeding does not increase the risk of SIDS, research has shown that breast feeding leads to a lower incidence of respiratory and intestinal infections, which are risk factors for SIDS.

While these measures are fairly straightforward, other precautionary measures related to SIDS have remained controversial, including the choice to co-sleep. The research on co-sleeping, or parents sharing a bed with their infant, is conflicting. Some doctors and researchers have urged parents to avoid co-sleeping due to research that suggests that SIDS rates are much higher when parent and child co-sleep, and the American Academy of Pediatrics (AAP) agrees that children should only sleep in their cribs. Yet other research, including a study conducted by James McKenna, PhD, at the University of Notre Dame indicates that co-sleeping may actually lessen the risk of SIDS if the right precautions are taken.

In many cultures co-sleeping is viewed as a vital part of the bonding process between parent and child, and some parents refuse or are reluctant to give up this loving experience with their child. Nevertheless, it is important for parents to recognize the risks that can be associated with co-sleeping in certain instances. Doctors recommend that co-sleeping is avoided under the following circumstances: if the parent(s) is obese; if the parent is intoxicated or taking mind-altering drugs (this may lessen the parent’s sensitivity to where the child is located in the bed); if the infant is put to sleep in a bed with other children; if the bed is a couch, daybed, waterbed or soft mattress; and in a sleeping area with sharp edges.

Though lots of precautionary measures can be taken, the cause of SIDS remains a mystery – many theories have been proposed and rejected, and research often leads to more questions. Yet despite this fact, scientists have identified a number of potential causes that might provide the missing link to understanding SIDS.

Possible Causes

In 1994, the National Institute of Child Health and Development (NICHD) launched a “Back to Sleep” campaign, encouraging parents to put their infants to sleep on their backs rather than on their sides or stomachs. It has been found that in the 11 years since the campaign was launched, the incidence of SIDS has decreased by nearly 50%. This overwhelming statistic has led researchers to believe that stomach sleeping is involved in SIDS – though not every child who sleeps on his/her stomach will be affected. Researchers believe that stomach sleeping leads to “rebreathing” when a pocket of stale air develops around the infant’s nose and mouth. According to Dr. Carole Marcus, a pediatric pulmonologist at the Children’s Hospital of Philadelphia, it is incredibly important for infants to sleep on their backs. “In some places where the population has really been persuaded to put almost all infants on their backs, the SIDS rate has plummeted to 1/3 of what it used to be,” Marcus says. “If all babies were put on their back and everyone stopped smoking, we would probably see almost no SIDS!”

A 2003 study conducted by Kaiser Permanente, NICHD and the National Institute on Deafness and Other Communications Disorders (NIDCD) and published in the American Journal of Epidemiology, found that side sleepers were twice as likely to die from SIDS, and those infants who were usually put to sleep on their backs and then later placed to sleep on their sides or stomachs were seven to eight times more likely to die from SIDS. "The message here is 'every night and nap time count'," said study co-author Dr. Marian Willinger of NICHD. "Parents and caregivers should place their babies on their backs every time they go to sleep. Consistency is the key."

Another NICHD study indicates that babies who die of SIDS might have been born with an abnormality in a part of their brain called the “arcuate nucleus” which might control breathing and waking during sleep. Another study points to the possibility that SIDS victims die from a lack of oxygen or an excess of carbon dioxide intake due to a possible combination of re-breathing carbon dioxide while lying on the stomach or stifled by bedding and failure of the brain mechanism that alerts the infant to wake up to breathe. Yet another study questions the possibility of a metabolic disorder which might prevent infants from processing fatty acids. One NICHD study shows that SIDS victims might have decreased binding of serotonin in the brain. Serotonin is a chemical which affects five regions of the brain that control breathing, heart beat, temperature and arousal.

The NICHD has also created a “triple-risk hypothesis” which suggests that infants who have died of SIDS are in a critical phase of development, are genetically susceptible to risks during this phase, and are affected by an environmental cause (such as stomach sleeping) which might weaken the infant’s already depleted defenses.

Studies also indicate that infants who were born to mothers who smoked tobacco have a much higher incidence of SIDS – it is possible that if an abnormality in the brain does exist it is more likely to be susceptible to the effects of low oxygen.

Though these various hypotheses have not yet led to a definitive cause, research is constantly growing closer to the answer. Yet due to the mysteries that still surround SIDS and its possible causes, many myths have been perpetuated over time, and parents are often misinformed about what risks really exist versus those that are simply just myths.

Myths Dispelled

One long-held myth is that immunizations cause SIDS. Some parents refuse to vaccinate their children because of this myth; however, a 2003 study by the Institute of Medicine’s (IOM) Board on Health Promotion and Disease Prevention found that there is no connection between immunizations and SIDS. Another common myth is that back sleeping is hazardous for infants. Some parents believe that when children sleep on their backs they are more likely to choke or spit up, but in fact there is no greater risk and back sleep is also better for an infant’s digestion. Parents also worry that back sleeping can lead to flat spots on their infants’ heads, but the NICHD suggests that if children get enough “tummy time” while they are awake the flat spots will generally go away a few months after the baby learns to sit up. Other myths have suggested that SIDS can be caught and is contagious, or that SIDS is caused by child abuse or neglect. Cases of abuse can be misdiagnosed as SIDS. It is important for parents to recognize truth from myth so that they can create the healthiest environment for their children.

While getting at the heart of what causes SIDS and what doesn’t is vitally important, it is also necessary to recognize the emotional effect of SIDS on a family who loses a child. SIDS is not simply a scientific term or a page in a medical book – it is a deep and tremendous loss that can turn a family’s world upside down.

Coping with SIDS

To lose a child is tragic, but to lose a child without knowing why can be devastating to parents. Some individuals wind up blaming themselves, even though they cannot identify what they might have done wrong. They remember when, only moments earlier, their child was soundly sleeping and involved in a normal daily routine. Oftentimes after losing a child to SIDS parents look everywhere for an answer – only to find that research is not definitive and cannot provide them with resolution. If you or someone you know has been affected by SIDS, there are many support groups available. First Candle/SIDS Alliance offers grief counselors 24 hours a day. You can speak with a counselor by calling 800.221.7437, or find one of the many online communities available where you can share your feelings with other families who have been affected by SIDS.

This article was published in the Fall 2005, Volume 7, Issue 4 of sleepmatters