0-6 months
Carrying your baby tummy to tummy is a position where the baby is held in a crouched position and is the most adequate method for carrying a newborn at least up to the age of 4 months. Your baby's back is kept well-rounded, as if still in the womb, while his knees are pulled upwards and his feet pointing down. This position is the same as when practicing skin-to-skin with your baby, which becomes possible as soon as he is at least 8 pounds, safely and easily. This crouched position will give him the comfort necessary to his sense of emotional security and is known to be beneficial to the development of his bones and joints. Before 6 months, the stretchy infant seat should be used to support the baby at a good height. Otherwise, you can also use the evolutive belt sold separately.
6 months and up
Starting at 6 months and when your baby can sit by himself, his spine is sturdy enough to no longer need constant back support. When he is tall enough, the newborn seat will no longer be needed and he will even be able to have his arms out above the shoulder straps.