SIDS is without a doubt the greatest fear of parents. SIDS is defined as the sudden death of a healthy baby while sleeping, which cannot be explained in any other way after all other options have been taken away. In other words, SIDS is a diagnosis of exclusion after ruling out all other diagnoses. There are no known interventions for SIDS (I.e., it is unclear whether you can “wake” the infant and prevent death). There are also no known biomarkers, that is, biological indicators to help identifying at risk newborns.
The only thing available is a long list of risk factors. Known risk factors include parents’ smoking / secondhand smoke exposure, parental substance abuse, poor nutrition of the mother, pregnancy crowded and more. In the 90s the “Back to Sleep” campaign aimed to reduce rates of sudden infant death proposed to put babies to sleep on their back.
The campaign was very successful and boasted in reducing the SIDS rates almost globally by 30-70%, however SIDS rates remain high and it is still the leading cause of death (3000 cases/year in the US, 270 cases/year in the UK).
Sleeping on the back yes or no?
Several articles have criticized the sweeping recommendation to sleep on their backs as well as the associative connection between sleep on their backs and SIDS for several reasons:
- As shown in the graph, SIDS rates were declining even before the beginning of the campaign.
- At a certain point, decline in the rates of deaths has plateaued despite the increase proportion of babies sleeping on their backs.
- The number of SIDS causes could have been declined due to a decline in other proven risk factors (e.g., smoking) and had nothing to do with back sleeping.
- During the time period of the campaign, the SIDS definition was split to three. The decline in SIDS was proportional to the increase in the percentage of deaths in other categories (i.e., SIDS cases were classified under a different names and there was no overall reduction in unexplained deaths).
- It still remains unclear why back sleep reduces deaths.
- Back sleep is less comfortable and results in disrupted sleep (which some claim saves them from SIDS).
- Sleep on your back may lead to neurodevelopmental delays and missing critical milestones. Daily “tummy time” is essential to help the newborn develop strong neck and arm muscles to they can lift their heads.
My personal opinion is prone (“tummy”) sleeping did cause deaths, but not necessarily SIDS. These deaths were the results of suffocating from poor bedding (lose sheet or soft mattress). Infant cribs may still contain choking hazards in the form of stuffed animals and decorative items. Supine sleeping has resolved these problems – but it did not reduce SIDS.
The triple-risk model
The most commonly used model to understand SIDS is the triple model. The model posits that a combination of two or three factors: a critical development period, babies with defects and environmental pressures results in SIDS.
However, SIDS has four main characteristics that the model does not explain:
- Boys die more often than women, at a ratio of 60:40.
- Hispanic infants have a 44% lower risk of SIDS than non-Hispanic whites and blacks.
- Most of the deaths occur within the first 2 to 4 months from births.
- Most of the deaths occur in winter.
The “wear and tear” model
Recently, I published an article that proposes a new theory for understanding SIDS, which explains the four characteristics of the syndrome. The theory is called “wear and tear” and posits that SIDS is caused by environmental pressures like pain, stress, and trauma. When these stressors cross a certain threshold of tolerance of the infant dies. Putting it differently, if you take a group of people and stress them over a long period of time, eventually all of them would die but not at the same time because each person has a different stress tolerance.
The “wear and tear” model thereby differs from triple-risk model in suggesting that all babies potentially at risk of SIDS and there are no mysterious genetic defects that eventually result in one’s death, at least not to the extent we see in SIDS. The theory also suggests that infants with low stress/pain tolerance would be at higher risk, but will survive if kept away from stressful/painful/traumatic experiences or treated with stress/pain management techniques.
This figure explains the new model. Painful/stressful/traumatic events creating a disturbance in the infant’s biological equilibrium (homeostasis). When the tolerance threshold is breached, death occurs.
Circumcision and SIDS
Circumcision is a surgery done without anesthesia and causes bleeding, market, trauma, pain, nerve partition, separation from the mother, a bacterial infection, damage to healthy tissue, and increase sensitivity to pain.
To the best of my knowledge, my paper is the first scientific article to suggest that circumcision leads to SIDS, however circumcision and death were always entwined and I suspect that SIDS can explain much of Jews early history, for example, their motivation to convert other populations to Judaism (to compensate for their falling numbers), which contrasted with the will to maintain a close religion.
My article was published in frontiers in Neurology and includes much more information on circumcision, SIDS, and other risk factors. It also includes references to all the information provided here.
The article is ranked #1 most-read paper in frontiers in Neurology since publication.