Thats bullcrap, they shouldnt be ever allowed to kick him out, you are allowed anyone you like in there, unless there is something very wrong where he could be in the way. If they ever try to do that again, say something, ask why he needs to step outside, because you would feel more comforted with him beside you extra... Its very discrimitary, if it was me in your siuation I would have asked why and if they tried to tell me he couldnt be in there I would demand he stay if they still refused I would have asked to see someone of higher authority... Its your pregnancy, your privacy, its not up to them...
Secondly that would be an awesome experience, I really hope that he will be there to hear it next time hun