E., at any point, did he sleep through the night? If they have sleep through the night before and now he is waking up in the middle of the night it might be something other than him being hungry. If his not hungry and you are feeding him because he woke you up, you may be training him that if he wakes up he gets to eat, that my cause problems when he is older and wants to still eat in the middle of the night. Once my kids showed that they could make it through the night, several nights (weeks)in a row, without a feeding then if they would wake up I won't feed them. I knew that they didn't need it. I know this sounds crazy, but out youngest son, who is 2, still wakes up in the middle of the night occasionally. Sometimes all he is doing is looking for his "plug" (pacifier). Other times he just happens to wake up and usually he will turn his music on in his crib and then he puts himself back to sleep. The music is the aquarium that attaches to the side of the crib, he's had it in his crib since he was 3 months old. Sometimes we have to go into his room and help him find his plugs, usually they have fallen under his crib, or just cover him back up because he is cold.
I am not disputing the fact that he might be hungry...I am just offering the idea that there might be other reasons and that he doesn't need to feed. Just becareful that your son isn't just training you to come into his room for company. I know one time I had to go into my son's room and sit beside his crib and hold his hand for a minute just to reasure him that I was there. Never had to get him out of his crib and he fell back to sleep. Good luck and I hope that maybe this helped a little. Congrats on the up coming little one.