Babies can become very attached to their favorite style of pacifier nipple. That's why all of the new closer to nature pacifiers have the same baby approved nipple, so baby can easily switch between different shield styles within the collection without any confusion. The nipple shape on the pacifier is more like a bottle nipple offering a more familiar feeling for baby. And, the symmetrical orthodontic shaped nipple was designed to improve balance making it easier for babies to hold the pacifiers in their mouth while supporting natural oral development. Tommee Tippee closer to nature recommends changing pacifiers every month and they should be thrown away at the first sign of damage or weakness. The closer to nature pacifier collection is available in a two age stages: 0-6 months which has a smaller nipple and shield shape for little mouths and faces, and 6-18 months which is the same shape, just larger, for growing babies. tommee tippee closer to nature recommends changing pacifiers every month and they should be thrown away at the first sign of damage or weakness.