Suitable from birth. Swaddle sleeping bag fits newborns 5 lbs-12 lbs. Machine washable lightweight Cotton fabric, ideal for rooms between 70-77° degrees. Officially acknowledged as “Hip-healthy” by the International Hip Dysplasia Institute. Can swaddle with arms in or out, for comfortable sleep all night long, bottom zipper opening allows for easy diaper changes. Award-winning design is reassuringly snug on top, while allowing for a natural leg position on the bottom.