Despite what doctors will tell you I've personally done enough research on vaccinations to say that they do not protect anyone from getting a sickness, we are all susceptible at any given point in time. Additionally vaccinations have mercury in them as well as animal byproducts which does more harm than good to our little ones. If you've had chicken pox twice before I would think you would have built a good immunity up against getting them again but you never know. I would say that your best protection against them is eating healthy and getting enough rest and exercise. Lots of veggies and stay away from sugar (weakens the immune system) are my best suggestions.
If I weren't working full time I'd bring my 8 month old over to expose him to chicken pox so he builds up his immunity to them. That's what moms used to do.
I do not know if chicken pox can have any effect on a pregnancy, I'd call your doctor on that one if you haven't already.