This baby sleep sack is designed for babies allowing them to sleep in a natural arms up position supporting self soothing and helping your baby establish a healthy sleep routine. The snug fit calms the startle reflex promoting deeper and more restful sleep making it an essential swaddle sack for newborns. Recognized by the International Hip Dysplasia Institute our newborn sleep sack provides ample space for leg movement ensuring the natural development of your baby hips. Our innovative button opening design allows for easy ventilation helping regulate temperature for your baby and the two way zipper facilitates quick and hassle free diaper changes without removing the entire baby sleep sack. Made from lightweight breathable material this sleep sack for newborns helps regulate your baby temperature reducing the risk of overheating.