Four Wheeling while pregnant

First let me start by saying I am not currently pregnant and I'm not looking for judgement . I know the dangers of doing anything along these lines while very pregnant can separate the placenta from your uterus. What I am asking is this:

My fertility week starts in a couple days and we are going upstate four wheeling for Valentine's day. If I were to get pregnant I'd be just about 2 weeks. I do not want to put my life on hold because there is a slight chance I may be pregnant. Do you think I should be worried or take it easy on our trip? We do off roading but no stunts and not very fast.