This question is related to How do dealing with infant flipping over during sleep training?, but not exactly the same.
Our 5 month old daughter flips onto her stomach constantly. When you put her down on the play blanket, she immediately flips onto her stomach AND props herself up with her arms. This is okay during awake times when she can play with toys, etc.
This becomes an issue when we try to put her down in her crib. She loves to flip over onto her stomach and pushing up with her arms. So, when she's in the crib, she's not even resting her head to try to sleep. (This is the part that differs from the above question). So, we can't put her down, unless she's already drowsy.
When we co-sleep with her at night (bring her into bed in the middle of the night when my wife nurses and when she's done, she stays with us) she sleeps between my wife and I. Her head level with our pillows. I would put her close to my stiff foam pillow so that it acts as a barrier for her so that she can't flip. :)
Is the only way to put a physical object next to her to block her from flipping? Even when she is partially swaddled (i.e. only legs are swaddled) she still can flip. She bring her legs up and swings to the right!
The issue is not that she is sleeping on her stomach, it's that she is propping herself up when she's on her stomach and can't put herself to sleep in that position. When we put her on her back, she returns to the propped up stomach position.