Our super soft baby sleeping romper comforts and grows with baby during and after the swaddling stage. It is made from 100% soft breathable cotton and is acknowledged by the International Hip Dysplasia Institute for its design which swaddles to waistline for a hip-healthy natural leg position. 0 to 3 months - It's a snug Swaddle, which cocoons your baby and helps to prevent startle reflex. It is easy to swaddle your baby with arms tucked in for total snugness or arms out. 3 to 6 months - It transitions to a cosy sleep bag. Unclick the poppers to free your baby?s arms and hands to allow them to self soothe6 months plus - Their favorite sleep bag becomes a Romper. Simply open the poppers at the bottom and baby is free to stand up and move about. The 2. 5 Tog Nite Nite romper also has a 2-way zip for easy changing, a chin guard and safe open/close clickable poppers and has a tog rating of 2. 5 for cooler nights Designed to make it natural for baby to move from swaddles to a sleeping bag.