I cannot count the number of women I know who ate sushi while pregnant. (Not one of those women's pregnancy was affected negatively by the consumption of raw fish.) I did not eat sushi while pregnant because, to my great dismay, the taste of fish/shell fish made me sick. I couldn't even be in the same room as cooking fish (fairly obnoxious as my SO is in the shellfish industry).
The concern, with sushi, is that it might carry food borne illness such as salmonella or ecoli. The risk is higher in foods that have not been cooked. Of course, other foods can also be contaminated. I remember there was an outbreak recently on spinach. Weigh the risks and benefits and feel it out for yourself. It's a personal decision.
I would suggest you are picky about where you get your sushi from and make sure their ingredients are fresh (which also will determine how good it tastes ;). Also, if you decide you're not comfortable with it, consider that there are many types of sushi that are cooked, unagi, for example.