Milk bottle teats by age

No need to change according to age, but rather baby’s acceptance and cue. And also what you’re feeding, for bm, you don’t have to upsize too fast as it’s quite thin compared to FM. When baby starts taking too long to drink/gets annoyed being unable to suck, that’s when you need to upsize. For ref (it will differ between babies): My lo is 25m and still using size 4 (Avent) teats. Previously she used size 0 till 3mo, then size 1 till about 7-8m followed by size 3 then 18m size 4.

For a start, yes use 0m+ because the teats are made for slower milk flow. If 6 months teats will have fast milkflow and may choke infant :) Afterwards, it depends on your baby preference.