Our super soft baby sleeping romper comforts and grows with baby during and after the swaddling stage. It is 100% soft breathable cotton and is acknowledged by the International Hip Dysplasia Institute for its design where is 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 snuggle up and 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 babys arms and hands to allow them to self soothe., 6 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.