It is worth keeping in mind, too, what counts as a risk factor. In the US, for example, it means any deviation from a specific set of circumstances: where a child found on their back in a crib or bassinet with nothing else other than a safety-approved mattress and fitted sheet. Some cases categorised as presenting risk factors might be babies co-sleeping with a parent who had misused alcohol or drugs while others might be simply a baby on her back in a crib with a teddy bear nearby.