Mr. Know it all.

My husband has become a Mr. Know it All about this pregnancy even though it's my body that's pregnant he knows it ALL!! He knows better than everyone how to measure a baby's progress and he knows exactly what day we conceived even though that's impossible. So when ever I get excited about how far along I am he's does this I don't give a f*ck humph because that's not how far along I actually am. I've explained it to him and everything but no such luck on getting him to understand because he's Mr. Know it All. Also everything I say is wrong, and his feelings are eggshells. This kinda dumb crap makes me lose my mind. I love my husband and this is not him. I mean it is but not on this scale. I don't know what to do besides buy him books he's not even gonna open because he knows it all. Help me not lose my mind, I don't know what to do but it hurts me that he's acting this way. I wanna enjoy this with him but how can I when everything I say is wrong?