As far as I know, it's 'normal' to have MS all the way through the pregnancy... for a few weeks... not at all... Every pregnancy seems to be different in this respect (although of course, there's a trend towards many getting it only in first trimester).

I had a week of feeling a bit yuck at about 7 weeks I think and then nothing at all but for the occasional sick feeling in response to strong smells. It really freaked me out too as I had a previous missed m/c and was scared that it was happening again. But no... I was just lucky!

Hopefully this is it for you and you're in for a happy, healthy and queazy-free pregnancy! All the best.