This study is about a year old.
If you understand the toxic gas theory (or even know it exists) this finding does not surprise you. Baby mattresses (crib, bassinet, pack-n-play, etc.) are made from the same chemicals as adult mattresses. Additionally, adult mattresses are also likely to be older (more used) than a baby mattress, which people often buy new. Even if an older (more used) baby mattress is used for baby, it's still only used by a child for a couple of years before it's traded for a regular bed. Adults sleep on their mattresses for decades, and have much more sweat accumulating (plus body heat) in the mattress than a baby mattress does. Ew. My point is, the more a baby mattress gets used, the more likely the mattress is to cause SIDS (see graph). So it makes sense that an adult bed would be even more likely to cause SIDS, since it is much more likely to be used for an extended period.The researchers estimated that about 88 percent of SIDS deaths while bed-sharing would not have occurred if the baby had not been bed-sharing."It's become really uncommon to encounter a baby who dies of SIDS who wasn't bed-sharing," Moon said.
The title of this article should really use "bed sharing" rather than "co-sleeping." You can safely co-sleep with your baby using a side sleeper aka "co-sleeper" with a BabeSafe wrapped mattress.