Nuk Orthodontic vented nipples are awesome.  I have three babies under three years old, and I just wish I had discovered these sooner.  When I had my third baby we, my husband and I, just assumed we would use the same bottles and nipples as we did with the boys but when we tried it would seem almost like she was drowning then she would have a bad belly ache and puke almost everything she had eaten up. We tried several other brands and finally my sister suggested Nuk Orthodontic Vented Nipples and I am so happy she did.  With the Nuk Orthodontic Nipples my baby can control the flow of formula...