We have used these bottle since my little one was born. I breast feed for 4 months and would use these when I pumped. Now that baby is 7 months and we use formula we still like them but they are not durable for the dishwasher so dont put them in there. The bottle will discolor and the words will come off. I find that they are difficult for the little one to grasp as well but if you use the grippers it is fine. He neve had problems with gas with these bottles.