When they do it on their own :)

I would say it's safe when they roll over and stay there on their own! You should never ever PUT a baby on their tummy to sleep.. but should they start to roll, sleep on their side and then eventually their tummy, that is most likely when it's fine to leave them be :)

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About Meg
Birth: September 29
On Moms.com since: Aug 5, 2013
I am a new Mama.. married to my sweet Husband! I am a barre3 addict and a Team Leader here on Moms.com! I feel so blessed to do what I love and live life with the ones who make it magical.