My little girl is about a month and a half old. When I put her to sleep one night I put her on her tummy... When she woke up she was on her back. I couldn't remember if I had gotten up in the middle of the night and put her on her back or not so I thought nothing of it. Later that night after she woke up and ate, I put her back down, again on her tummy, and within a minute she was on her back... I couldn't believe it! And she not only did it once but three times! And here I though babies weren't supposed to do that until they were at least 3 months old.