I've been worried about the same thing - I've been swaddling her for some of her day sleeps but I find DH particularly being a whack heavier than me, makes a dint in the bed mattress and DD could roll into him without her little arms to stop her so haven't swaddled at night for that reason - but if she's up between the pillows as others do, I could - that and (naughty, naughty me) but DD usually sleeps on her side, (which she can't do when swaddled) it's the way she likes it naturally though, she squirms into that position herself and her arms stop her rolling on her tummy so I let her sleep that way..