When can I start carrying my child on my back in Baby Carrier One? Emily M. 25 August 2022 21:13 Once your baby is 12 months old, he or she is big enough to be carried on your back in Baby Carrier One. Related articles Can the seat width be adjusted on Baby Carrier Harmony? How do I put on Baby Carrier One? What is the difference between Baby Carrier One and other BABYBJÖRN Baby Carriers? Comments 0 comments Article is closed for comments.