Question: I'm exclusively breastfeeding my baby, and occasionally give him pumped bottles. I generally try to warm them up before giving them to him, at least to room temperature. (I was once told as a tip to get babies used to room-temperature bottles right away, just in case sometime you don't have a way to heat it up...) Sometimes, though, he is frantically crying as I'm trying to warm up the bottle... Is it ok to give him a cold bottle? He doesn't seem to mind, and drinks the whole thing. Are there any problems with feeding a 2-3 month old a cold bottle?

Answer: 
Yes, you can feed your baby a **room-temperature** bottle.  

No, you should not feed your baby a **fridge-temperature** bottle.

The reason is that infants are very small bodies, so temperature differences are more significant to them than to older kids or adults. 

Infants can't handle a steaming hot cup of tea, just like they can't handle milk that's just a few degrees above freezing. The closer to the natural body-temperature their food is, the easier they can handle it. 

By the way, the same idea applies to bath water. (For bathing, not drinking!)
I can't provide any supporting evidence, but I can tell you that at my very first pediatrician appointment with my first son, I had this exact conversation with my pediatrician. 

I live in Southern California (a warm climate anyway) and my son was born in the summer, so the weather was quite warm. My son started fussing a bit, and I was having typical new mom anxiety because I didn't have anyway to warm his bottle (I wasn't good enough at breastfeeding to do that in public yet). I asked my pediatrician if they had some way I could warm the bottle, and his response "Would you want to drink something warm when it is this hot outside? I bet your son would also prefer his drinks cold." 

That was the last time I heated any bottle for either of my kids.