I suppose suffocation can happen. I take care of a newborn. A few days ago, he fell asleep before I could swaddle him. So I covered him with a receiving blanket and just kind of tucked it around him. When I came back to check on him, the blanket was covering his whole face. He had been wiggling his legs, and it just worked itself up. Very creepy to look at. He was/is fine, but I don't ever want that to happen again. It's no reason to panic, of course. But we do need to be careful.