I know this isn’t the most fun topic. On the other hand, SIDS remains one of the leading causes of death for infants under one year of age and the information that we as parents are given is usually vastly oversimplified and even misleading. I personally feel like every parent has the right to know clinical information about SIDS, how it is diagnosed and what we may possibly do to prevent it.

What is SIDS?

SIDS is one diagnosis under a larger umbrella of diagnoses called Sudden Unexpected Infant Death (SUID). SUID includes infant death from a number of different causes including accidental suffocation/strangulation and even child abuse.

How is SIDS diagnosed?

This is a very subjective question. Officially a diagnosis of SIDS is made when a death does not meet any other known criteria such as an illness, accident or child abuse. The definition of a clinical case of Sudden Infant Death Syndrome is defined as the sudden death of an infant younger than 1 year that remains unexplained after a thorough investigation, which should include an autopsy, examination of the scene of death and review of clinical history. With such a broad clinical definition and no known cause, diagnosing SIDS can be highly subjective.

The medical community has been getting better about more precise diagnosis of SIDS, but it hasn’t always been that way. According to the Centers for Disease Control’s manual for investigating SIDS cases, many of the cases that were once diagnosed as SIDS were probably more accurately diagnosed as accidental strangulation or suffocation, meaning that the much lauded decrease in SIDS may not be an actual decrease, but simply more careful diagnosis of accidental deaths.

Clinicians and law enforcement have been subject to their own biases in diagnosing SIDS. A young African American couple was charge with murder and child abuse when their baby died, though there were no signs of abuse or neglect. The charges were eventually dismissed, but only after the parents had spent six months in jail because they were unable to post bond. On the opposite end of the spectrum are white, married, middle class women like Mary Beth Tining and Waneta Hoyt whose babies died under suspicious circumstances with indications of child abuse, however, these deaths were initially attributed to SIDS. However, these were later found to be infanticide when more careful investigation was performed.

OK… That sounds kind of vague, how do they tell the difference then?

So to get technical, in a case of actual SIDS (as opposed to abuse)  findings have shown petechiae (small, red spots that are a symptom of bleeding beneath the skin) on parts of the lungs and heart with no difference in severity between babies who died face up, face down, or side-lying. 

The petechiae are a symptom of what doctors call central airway failure and are not consistent with airway obstruction as is the case with suffocation or asphyxiation. What the autopsies seem to be showing is that SIDS is not caused by the baby’s airway being blocked, but rather, the respiratory system shutting down from within and that it happens regardless of the baby’s sleeping position. According to Medscape’s overview of clincial presentation and physical examination of SIDS , other findings of clinical presentation before and after death include:

  • Many SIDS babies had seemingly minor cold/flu symptoms, lethargy, irritability, or changes in crying in the weeks preceding death. 
  • Infants who have died of SIDS often display a frothy, blood-tinged discharge from the nose or mouth at the time of discovery. 
  • Petechiae on the thymus, pleura, and epicardium. 
  • Baby was put down to sleep and found pulseless and apneic (stopped breathing during sleep, failed to arouse from sleep). 
  • After thorough examination and autopsy, no cause of death is found.

These symptoms do bear a resemblance to autoimmune encephalitis, an infection of the brain:

According to the online Merck Home Manual, encephalitis is caused by bacterial and viral infections or autoimmune reactions triggered by infections or vaccine reactions.

Still there are a number of biases that remain diagnosis, a baby found sleeping on its stomach may be assumed to be a SIDS case when there could be other explanations, or SIDS may be ruled out because a baby was found on its back. A co-sleeping baby could be diagnosed as SIDS even if there could be other explanations. Current recommendations on signs indicating child abuse and neglect are also highly subjective. For example, having a baby outside the hospital or a late arrival to the hospital does not mean that the parents are abusive or neglectful and having a baby in a hospital does not mean the parents are caring and attentive. (Just like being young and African-American doesn’t make parents abusive and being married, white and middle class doesn’t make a woman a caring and attentive mother.)

What about co-sleeping?

There is a strong bias against co-sleeping in Western cultures that has likely influenced existing medical literature. In his paper on SIDS research, Dr. James J. McKenna of the University of Notre Dame pointed out that if co-sleeping were truly as hazardous as medical authorities say, then none of us would be here because our ancestors would have died. (By the way, whatever your thoughts on co-sleeping, this paper is a very interesting read and I highly recommend it. It is pretty long and detailed, so be prepared to read it over a couple of sittings.)

He explains that in Europe and North America co-sleeping fell out of favor due to social and cultural pressures rather than any actual health issues. Among impoverished families, infanticide was rampant. Many parents tried to avoid jail by claiming they had accidentally overlaid the baby in their sleep. This became so much of a problem that during the 17th century, England, Germany and France all passed legislation mandating jail time if a parent was found in bed with a child under two years of age. 

In fact, babies protest very loudly if their breathing is compromised in any way. According to Dr. McKenna, it is likely that only a parent who is intoxicated or otherwise unusually lacking in their ability to wake up would not notice a screaming baby next to them.

Moralists of this era were also concerned with the “sexual purity” of children and thought that getting children out of their parents’ bed would remove the temptation for incest. Also, a growing philosophical movement that placed the spousal relationship in competition with that of the mother and child also contributed to the end of the family bed in Western society.

Because of the stigma attached to co-sleeping, adequate research comparing co-sleeping and separate sleeping infants and SIDS is difficult. Many parents sleep apart from their babies because they have been told it is safer and many who do co-sleep don’t “advertise” for fear of criticism from family, friends, doctors and even child protective services.

Between the stigma attached to co-sleeping and the massive amount of funds involved, Dr. McKenna’s opinion is that it would be extremely difficult to find the 10,000 co-sleeping infants needed to compare with an equal sized group of infants who sleep apart from parents for a study to really get an accurate picture of the risks.

There is statistical and laboratory evidence that co-sleeping may prevent SIDS. McKenna found that when babies and mothers sleep together, they tend to match sleep patterns and even bring each other out of apneas (periods when breathing stops). He and his colleagues also found that internationally, among cities where SIDS deaths are the lowest, co-sleeping rates are some of the highest. Among native peoples who practice co-sleeping there has not been an increased rate of SIDS observed.

Historical evidence also presents problems with the idea that SIDS is related to co-sleeping. Early terms for SIDS included “crib death” and “cot death”, which imply that the baby died in a crib or infant sleeping cot. These terms would not likely have come into common usage if the typical case of SIDS was found in the parents’ bed.

What’s an ALTE?

An ALTE is an “apparent life-threatening event” in an infant characterized by the sudden onset of a combination of symptoms, including apnea, change in color (pallor, redness, cyanosis (a.k.a. blueness), plethora (excessive blood leading to swollen or flushed presentation), change in muscle tone (floppiness, rigidity), choking, gagging, or coughing. Earlier in the 1980’s it was thought that these incidents might be a SIDS case in process, but research couldn’t provide a definite link between the two. The exact incidence is unknown, though estimated to be somewhere between 0.5% and 6% with most cases occurring in infants under ten weeks of age. Boys are more frequently affected than girls. (This is a similar time frame as SIDS, which peaks at 2 and 4 months.) Babies older than 2 months who had an ALTE or who had recurrent ALTE episodes had a higher incidence of significant disorders.

About 50% of ALTE cases have known cause, which means that ongoing observation may be needed to prevent further illness, injury or death. In another 50% the cause is found. GERD, febrile seizures and heart abnormalities are common causes.

Many babies who experience an ALTE don’t have any long term problems. But an ALTE can be a sign of a more serious condition or the possibility of SIDS. From the above cited  AAFP article: “Various studies report the percentage of children who died of SIDS with a previous ALTE to be between 4 and 10 percent, although one study that focused on children of nurses reported that 27 percent of SIDS victims exhibited previous ALTEs.”

One hypothesis I have is that the AAP’s new recommendation that babies sleeping in their parents’ room can reduce the risk of SIDS is that when a baby is in under closer surveillance, episodes of ALTE may be more likely to be noticed and prompt care may reduce the risk of SIDS. Nothing proven, but a hypothesis.

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