Disconnected daddy

Has anyone else experienced your partner disconnecting from you after you got pregnant, his excited when he talks about our son arriving and he talks to everyone about him coming and goes and buys things for him, this was a planned baby and we have been together for quite a long time, I'm just concerned as he seems to be withdrawing from me he doesn't talk to me or interact with no matter how hard I try to include him, talk to him, do things he enjoys, I'm starting to really worry that maybe it's got more to do with me then the baby. Has anyone else delt with this? Can anyone suggest anything I can do?