Different pacifiers for different kids, but this one works for us. We didn't want to use pacifiers, but baby was hospitalized at birth and the NICU staff used this one to help baby strengthen muscles to learn to eat. Baby still takes this one when sleepy. The sizes (0-3 months, 3 months plus, etc.) are just guidelines. Baby's size will ultimately determine which pacifier they'll use, much like the way clothing sizes are relative. There is a preemie size available if needed, but our kid was started on the 0-3 right away and is still on it at month 5. If you choose to, or have to, use a pacifier, this is a good one to try. Quality material and not pricey. It won't break the bank if you decide this isn't the option for you. (And the color options are cute.)
The soothie is one of the only pacifiers my son will take.. It really helps soothe him and calm him down. Most of the time he will not take a nap without one of these in his mouth. I especially like the vanilla scented ones.