Would it really be unsafe to eat sushi while pregnant?

i just found out im pregnant about 4 weeks ago, i was ecstatic and so was my fiancee! the only thing is i heard im not allowed to eat sushi because of harmful risks to the baby. i grew up eating sushi all the time and i love it. not to mention i've been craving nothing but asian foods which obviously includes sushi. i just really need to know if its really off limits