We've just arrived at our holiday accommodation and the travel cot mattress once we've put our sheets on it (we had to bring our own) makes it a bit bumpy. It's where the mattress folds away and the sheets are fitted, it pulls the mattress in a bit and makes it lumpy where the mattress folds. So it's technically not completely flat. Just worried as a first time slightly anxious mum and not sure how flat flat should be to be safe! Baby sleeps on his tummy (although we always lay him down on his back) Thank you x