DS2 is nearly 9 months. He turns from his back to his tummy when half asleep and ends up sleeping on his tummy quite often. He cant roll back over though, so when he wakes up he yells for me to rescue him quite loudly!
I assume its safe at his age to let him sleep however he wants to, including on his tummy. But is it a worry that he cant roll over?? He can obviously lift his head well.