I was so excited about using the glass bottles to feed my newborn. Especially with all the drama and reality of BPA in the plastic and was annoyed about the potential danger we all put out kids at risk. I bought these and loved how easy they were to clean and sterilize, however when I told the Dr they seemed less than thrilled. My daughter had a lot of gas, which I'm thinking most babies do as did my first and he explained that if there was too much air getting into her as a result of the type of bottle it was and suggested I use the drop in bags which I was very opposed to at the time. However after pain in my daughter I did switch to the drop ins and have found that they are helpful. I do use the glass though to store my milk in when I need to go places so that its n'ot in the drop in plastic for any length of time. So I think its a good investment as far as storing but as far as drinking I dont know just see how it goes. I was sad it didn't work out for us because i love the idea of using less byproducts. But its not for everyone I suppose!