The pacifier manufacturer NUK developed the orthodontic pacifiers which, because of their shape, fit into the child's mouth in the same way as the mother's nipple during breastfeeding. This means the pacifier is good for the child's mouth and gentle on the palate, gums and jaws.
The sizes are approximate
Orthodontic pacifiers size 0 (0-2 months)
Orthodontic pacifiers size 1 (0-6 months)
Orthodontic pacifiers size 2 (6+ months)