Is buttermilk ok to drink?

I know a lot of people will think this is gross, but I was raised drinking buttermilk. I don't do it often but every once in a while I'll buy a 1/2 gallon. It's pasteurized so it should be ok. But now I'm wondering if I should drink it while pregnant since its sour or whatever. I don't see my OB till march 2nd to ask.