Sushi?

Ok so I know that sushi is one of things pregnant women are told to stay away from. I've been doing a lot of research on the topic and from what I've read it seems like the practices in the US are to flash freeze to kill the harmful substances and in Japan sushi is encouraged throughout pregnancy. Does anyone else have any thoughts about this? I plan on talking to my doctor to get her opinion but I'm curious if anyone else has looked into this. Sushi seems to be the one healthy thing I've been craving even when sick! Thanks ahead of time for any insight.