Yes, sleep sacks are considered safe and recommended for newborns when used properly. Look for sacks designed specifically for the newborn stage that allow for swaddling arms in. This provides the snug security newborns need while eliminating loose blankets. Choose an appropriate TOG rating and lightweight breathable fabric to prevent overheating. Follow all manufacturer instructions. Check neck openings allow comfort but contain baby.
Sleep sacks themselves are not a SIDS risk. In fact, sleep sacks are considered safer sleepwear options for babies compared to loose blankets or traditional swaddling. They help reduce the risk of SIDS by eliminating the hazards associated with loose bedding.
Zip up swaddles are considered a safe swaddling option when used properly according to guidelines. The zipper secures baby snugly, eliminating risks of loose bedding. However, always place baby on back without bedding under or over the swaddle. Stop swaddling once baby shows signs of rolling over. Only do one layer and avoid overbundling.