when to move onto size 4 teats

[nappyaddict]

i asked my mum to get ds some new teats today (avent ones) and she bought the wrong size (4 instead of 3) i was thinking maybe i could move him onto the next size but i'm not sure. how old was your lo when they went on to size 4?

Doesn't really matter what age you swap - it all depends on the speed of the milk flow and whether their sucking rate can cope with the amount they are getting in their mouth. Give it a try and if it starts to flood or leak out the sides its too quick, if it takes an age for the bottle to go down then its too slow - if not then OK to continue.
I found very little difference bewteen size 3 and 4 Avent teats.

Hi Nappyaddict. E went onto variflow teats from a fairly young age. They were sort of all in one and the flow depended on which way you held the bottle up. I found this way you could choose the flow depending on the day she was having iyswim. I agree though, hardly any difference between 3 and 4.