Everyone has there faults, nobody is perfect I'm sure he doesn't realise how much it irritates you, have a talk about it with him
I think a lot of men are like that. My husband is like that as well and it as well irratates me. Its almost like he means to do it cause I always mention it, but yet he still does it. Also when you are pregnant your hormones are out of wack and things irratate you more then usual.
Tell him an earlier time so maybe he will be there when you need him to be.