Though one of the concerns with a bumper is the baby rolling into it, the other concern that has been linked to SIDS is the air flow in the crib. That is why the breathable ones are also a benefit, it promotes air circulation.
The recommendation is to remove it once the baby can roll.
This makes sense as far as the baby getting stuck up against it, but like the OP pointed out, it's not JUST that. It's the fact that airflow in the crib (whether baby moves or not) can be compromised. That and, as many moms have pointed out to me and others, you never know when they are going to start moving. It could be a freak accident. Do you want the first time they start moving and rolling to be known b/c all of a sudden they're stuck against a bumper? What is the point of having it in there in the first place is one thing I just haven't been able to figure out. Babies start rolling at different times.
Re: A note on bumpers and safety
I've heard keeping a fan on in the room can help with the circulation issue, so that is what we plan on doing.
Thanks for the PSA.?
The O'Baby Blog
This makes sense as far as the baby getting stuck up against it, but like the OP pointed out, it's not JUST that. It's the fact that airflow in the crib (whether baby moves or not) can be compromised. That and, as many moms have pointed out to me and others, you never know when they are going to start moving. It could be a freak accident. Do you want the first time they start moving and rolling to be known b/c all of a sudden they're stuck against a bumper? What is the point of having it in there in the first place is one thing I just haven't been able to figure out. Babies start rolling at different times.