My baby is 4 months old and we use the Avent bottles. I'm just a bit confused as to when we should switch to the next level of the nipple flow. We use the level 3 as of right now. He seems to be ok with it. But I remember reading some where that you have to switch out the nipples every 3 months or so. Also when he drinks he's milk sometimes he sucks so hard that the nipple sucks in. As if he is sucking to hard. Not sure if that was useful information but I thought I would throw it our there.
I agree with junkenpo. There's really no way to tell for sure. Just try the next level and if it works, keep it; if it doesn't, switch back. With DS, we switched to level 2 really early -- he had a very weak suck, and with the level 1s, it would literally take 45-70 minutes to finish a bottle. Then I think we just stayed on level 2 forever. I don't remember if we ever even went to level 3. I'd say if he's collapsing the nipple, he's probably ready for faster flow, but you won't know till you try.
It depends on your baby, if he's not frustrated with the current nipple flow, I see no reason for changing it. With DS, however, I was clueless so I just followed the recommendation listed on the back of the packaging (we use Dr. Brown bottles, btw) - level 1 up to 3 months, level 2 up to 6 months, level 3 up to 9 months, and level 4 for 9+ months. In hindsight, not sure if I HAD to. DS was drinking 8 oz bottles by 9 months, using level 3 without a problem. We could have continued with that, I think, unless DS showed a clear sign of frustration.
I have to agree if he is sucking that hard and its not flowing as fast as he is liking then maybe its time to switch it up. My son used Avent and if I remember correctly he did not get to 3 until about 4 or 5 months old and that only lasted about a month then we went to 4 for the remainder of his time with bottles. But babies will let us know if something is not working and that's my clue to try something else.
i tried changing the nipple to the next size 2 times .. and both times my daughter found the flow too fast and would end up vomitting ... therefore we went back to the small size .... and she is 15 months now ... and she seems to be fine with the size ...