This article mentions that the Snoo was designed to prevent SIDS, but the number one factor predicting SIDS is a used mattress... and interventional studies have proven it is not caused by other confounding factors like poor familes or second children being more likely to have used mattresses- It can be prevented with a new mattress or non-permeable mattress cover.
The Snoo has an integrated mattress in a non-standard size, but you can buy new replacements from the manufacturer.
> the number one factor predicting SIDS is a used mattress
As a three-time parent who did extensive reading on SIDS prevention before the first one and brushed up before each of of the other two: What?
Do you have a citation for this? Because my recollection is that all of these show up on the list of things to avoid for SIDS but a used mattress never featured once in my reading:
* Smoking
* Fuzzy stuff in the bed (stuffed animals, blankets)
As an anxious parent and an academic scientist, I did a deep dive into the peer reviewed literature on causes of SIDS when I first became a parent, which admittedly was a few years back.
I came across what is called the "Toxic Gas" theory of SIDS, which is admittedly not part of the major recommendations for avoiding SIDS in the USA- but I read all of the literature on it, and I found the evidence quite convincing, and the dismissals to be lacking. There were however dismissals in many popular review articles and mainstream recommendations, but they never presented an articulate rebuttal of what seemed like a reasonable concept, and convincing evidence.
The idea is that fungi in an older dirty mattress metabolize flame retardant compounds and produce toxic gases, which were measured in high concentrations with a mass spec on the surfaces of mattresses where infants had actually died from SIDS[1].
Other studies found correlations with mattress age after controlling for other variables, and decreases in SIDS rates with interventions based on non-permeable mattress wraps [2, 3].
Thinking about it fits neatly with some of the other risk factors you mentioned, as they reduce airflow, or put the infants face closer to the mattress surface.
I think it needs a lot more systematic studying, but it seemed convincing enough for me to buy a new mattress without phosphorus, arsenic or antimony containing flame retardants.
I'm not 100% sure about this theory, but I would not let any infant in my care sleep on an old mattress, or a mattress with potentially toxic flame retardants.
Surely there isn't one single "cause of SIDS" as it is just death, and any person can suddenly die at any age for any number of different reasons.
That idea is missing something- one of the most basic physiological responses is panic when blood CO2 levels get high. A baby that isn’t getting fresh air should be really upset- crying, flailing, etc. which would move them away from the surface and or bring adult help. What is the cause for this system not engaging in these situations? These studies are actually measuring neurotoxins at concentrations expected to cause this, in the boundary layer of the actual mattresses babies died on. But I could imagine it also happens that in some newborns, perhaps this low CO2 response or the ability to act on it isn’t developed yet?
How do you explain the fact that SIDS rates have dramatically dropped as we've rolled out the mainstream recommendations that don't mention anything about fungi or used mattresses?
I already explained that in my long description above- most of those mainstream recommendations make sense in the context of improving airflow and ventilation.
These ideas and interventions are in no way mutually exclusive: the mainstream recommendations are mechanism agnostic, they are just doing things that have been shown to work. And the toxic gas theory also doesn't claim to explain all causes of SIDS, so if some interventions work but don't fit with that framework, it would suggest a possible additional mechanism. For example, I wonder how the smoking and heat fit in as factors since those are factors I would expect would lead to people trying to ventilate more, but I don't really know what behaviors like that correlate with those.
After hearing about this theory, my first thought was that ceiling fans should also be extremely effective at reducing SIDs rates, and it turns out they are massively effective- reducing rates by 72% [1].
As simple explanation is most recommendations pretty much come down to “less stuff with the baby”. That’s fewer opportunities for bad air to become trapped near the baby.
This is largely my hypothesis above. Remove bumpers. Remove blankets. Remove the opportunity for bad air to become trapped.
The Snoo has an integrated mattress in a non-standard size, but you can buy new replacements from the manufacturer.