You can definitely bring the pouches in a carry on for a baby, as it's considered baby food. I always packed these items separately and declared them at security. TSA would check them over separately and we'd be on our way. Now that my kids are preschool age and older, I don't know that they would be as accommodating, but those pouches sure are convenient for the younger kids! Happy travels!
Here is the rule exemption from the TSA site.....
3-1-1 Liquids Rule Exemption
Formula, breast milk and juice in quantities greater than 3.4 ounces or 100 milliliters are allowed in carry-on baggage and do not need to fit within a quart-sized bag. Separate formula, breast milk and juice from other liquids, gels and aerosols limited to 3.4 ounces. You do not need to travel with your child to bring breast milk.
Ice packs, freezer packs, frozen gel packs and other accessories required to cool formula, breast milk and juice are allowed in carry-on. If these accesories are partially frozen or slushy, they are subject to the same screening as described above. You may also bring gel or liquid-filled teethers, canned, jarred and processed baby food in carry-on baggage. These items may be subject to additional screening.