If under the sheet it should be fine, just make sure that her feet are at the very bottom of the cot and should she bend her legs up she wouldn't get wedged in with the pillow coming up her head as this could cause over heating.

Another thing to try is a foam wedge under the sheet as less springy than a pillow and graduated so no fat edge to catch her if she moves down it.

My DD2 (17 wks)has silent reflux and has been sleeping propped up on a pillow in our bed, OH is on the sofa. Last night I put a pillow in her cot but under the fitted sheet and she slept relatively well in there (all other methods like propping cot up one end, towel or pillow under mattress haven't helped).

why are pillows not recommended is it risk of suffocation so by putting under fitted sheet it's ok or are there other reasons...(e.g. head get too hot).

can't find much on google other than not recommended for baby under 12 mths...

thks