The bassinet is well-made so it would be silly to throw it out after 2-3 kids. The fact that the resellers are other parents makes me trust a little more that they aren’t selling a broken/dirty bassinet, so why buy new for double the cost?
They are a victim of their own success.
The Snoo has an integrated mattress in a non-standard size, but you can buy new replacements from the manufacturer.
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)
* Sleeping on stomach
* Heat
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.
[1] Sudden Infant Death Syndrome: a possible primary cause https://www.sciencedirect.com/science/article/pii/S001573689...
[2] Used infant mattresses and sudden infant death syndrome in Scotland: case-control study https://www.ncbi.nlm.nih.gov/pmc/articles/PMC131017/
[3] Cot Death—Cause and PreventionExperiences in New Zealand 1995–2004 https://www.tandfonline.com/doi/abs/10.1080/1359084040001683...
I wonder if it’s a situation where bad air basically gets trapped by the baby. Not much different than, a CO2 canister leaking into a closed room.
I can believe that in certain circumstances fungal spores can also cause breathing problems, but I'm extremely skeptical it's the #1 factor.
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].
[1] https://www.nationwidechildrens.org/family-resources-educati...
This is largely my hypothesis above. Remove bumpers. Remove blankets. Remove the opportunity for bad air to become trapped.