Cats are funny. They know when things are changing. A baby will be a big change and the fact that you are home now is a big change from the daily routine. I would try and spend as much time as you can with him reassuring him and helping him to adjust to the new routine. Maybe some toys would be a distraction too. Also, when the time comes that you have the baby, it wouldn't hurt to bring a blanket or some item that has the baby "smell" on it home to your cat so that he can familiarize himself with it so it won't be a shock when the baby does come home. Congratulations, welcome to PT and best of luck!