It's generally not considered safe to consume ocean shellfish or other ocean sea food while you are pregnant. The reason for this is because they could contain high levels of mercury which would be lethal to the fetus. And with recent events, there is a lot of radioactive chemicals and chemical dispersants in most ocean seafood, so it's best to avoid it.
You can eat Fresh Water seafood though, I'm not sure what other name to use besides seafood though? Fresh water fish, crustations and the like are safe to eat during pregnancy.