I think that is extreme. 12 mos. Lordy I guess they can't be covered until they are walking. A newborn, I can see but 12mos. I don't think so. I used the sleeping bags for my kids when they were small and then the footed sleepers till I couldn't get them big enough but I did it because they wouldn't stay covered and at that time we lived in a cold climate. I would think that little ones would fall and hit their heads on the side of the cribs when they try to pull up. I guess all children should be raised in warm climates till age 1, they won't need blankets :-D