Rollercoasters during early pregnancy?

We're planning to TTC in a couple of months and we're also planning a vacation a couple months after we start trying. My fiance asked about riding rollercoasters while pregnant because an amusement park trip was talked about. I've read mixed things regarding rollercosters in early pregnancy. My fiance feels as though being only 3-7 weeks pregnant and riding a rollercoaster would be harmless and some websites agree. I know some women don't know they are pregnant and ride them and go on to have healthy pregnancies. Personally, I wouldn't be able to ride a rollercoaster while knowing I was pregnamt and being aware of the tiny chance that something could go wrong, even if I was very early along. I'll test before our trip like a crazy woman and rule our chance of pregnancy before deciding if we will go or not. I don't want to risk anything even if there's a small chance! What are your opinions on riding rollercoasters in the very early stages of pregnancy?